一个简单的学生成绩管理系统（我的第一篇博客）

学生成绩管理系统Demo，android+servlet（前端+后台）

一个简单的学生成绩管理系统

Hello，这还是自己第一次写博客，有点小激动~
一个完美的系统的展现是源于知识的积累沉淀，感觉自己还是个android知识小白，虽然这个管理系统不是那么完善，但是也花了一些时间，分享给大家，请大家多多指教哈~
我这次使用的是androidstudio和intelliJ IDES,这个系统分为教师和学生登录，我暂时完成了教师端的一些功能。后台servlet连接了数据库
以下展示后台代码目录和android代码目录和mysql
（1）后台代码目录
（2）android代码目录（学生端代码没有实现，不展示了）
（3）数据库五个表

android端代码如下

首先来看看我们的登录注册吧
先展示一下下图片哈~

代码如下：
（1）Register1Activity：
package com.example.management;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.example.management.Student.StudentHomePageActivity;

import com.example.management.Utils.StatusbarUtil;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class Register1Activity extends AppCompatActivity implements View.OnClickListener, RadioGroup.OnCheckedChangeListener{


public static final int Teacher_OPTION = 1;
public static final int Student_OPTION = 2;
private String str_username = "";//获取用户名
private String str_password = "";//用户密码

private EditText editText_accountr;//注意实例化的位置
private EditText editText_passwordr;//

private Button register;
private Button jumpToMainr;
private RadioGroup radio_group;
private String code;//服务器返回的值
int flag = 0;
int time;
private Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        //Log.d("123456", "handleMessage: "+msg.obj.toString());
        code = jsonToJsonObject(msg.obj.toString());
        Log.d("hander", "code: "+code);
        if (code.equals("0")) {//登录成功，跳转主页面
//                MainActivity.isLogin = true;
                //保存当前信息
                Log.d("handler", "登录成功");
//                Bundle bundle = new Bundle();
//                bundle.putString("id", id);
//                bundle.putString("account", str_username);
//                bundle.putString("password", str_password);
//                bundle.putInt("option", msg.arg1);
//                bundle.putBoolean("status", true);
//                UserInfoUtil.saveCurrentInfo(getApplicationContext(), bundle);
                Toast.makeText(Register1Activity.this, "注册成功", Toast.LENGTH_SHORT).show();

            if(flag==Teacher_OPTION){
                Intent intent1 = new Intent(Register1Activity.this, TeacherHomePageActivity.class);
                startActivity(intent1);
            }else if(flag==Student_OPTION){
                Intent intent = new Intent(Register1Activity.this, StudentHomePageActivity.class);
                startActivity(intent);
            }
            //finish();
        } else if(code.equals("-1")){//若注册失败，清空输入框，提醒用户重新俗人
            Toast.makeText(Register1Activity.this, "账号已存在!", Toast.LENGTH_SHORT).show();
            editText_accountr.setText("");
            editText_passwordr.setText("");
        }else if(code.equals("-2")){
            Toast.makeText(Register1Activity.this, "系统繁忙，稍后重试！", Toast.LENGTH_SHORT).show();
            editText_accountr.setText("");
            editText_passwordr.setText("");
        }
        return true;
    }
});


public String jsonToJsonObject(String json) {
    Log.d("hello", "jsonToJsonObject: " + json);
    String code = "";
    String message = null;
    try {
        JSONObject jsonObject = new JSONObject(json);
        code = jsonObject.optString("code");
        // message = jsonObject.optString("message");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return code;
}


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_register1);
    initView();
}

/***
 *布局初始化
 */
private void initView() {

    StatusbarUtil.setTransparentWindow(this, false);
    register = findViewById(R.id.register_btn);
    editText_accountr = findViewById(R.id.account_register);//须再onCreate里实例化
    editText_passwordr = findViewById(R.id.password_register);//须再onCreate里实例化
    jumpToMainr = findViewById(R.id.jumpToMainr);
    radio_group = findViewById(R.id.radio_group);

    register.setOnClickListener(this);
    jumpToMainr.setOnClickListener(this);
    radio_group.setOnCheckedChangeListener(this);
}




private void sendRequestWithOkHttp() {

    str_username = editText_accountr.getText().toString();//getText()要放到监听里面//获取用户名
    str_password = editText_passwordr.getText().toString();//获取用户密码

    new Thread(new Runnable() {
        @Override
        public void run() {
            try {

                if (flag == Teacher_OPTION) {
                    Log.d("mode", "run: " + flag);
                    requestNet(str_password, "http://10.161.66.7:8080/three/servlet/RegisterTeacherServlet?", Teacher_OPTION);
                } else if (flag == Student_OPTION) {
                    Log.d("mode", "run: " + flag);
                    requestNet(str_password, "http://10.161.66.7:8080/three/servlet/RegisterStudentServlet?", Student_OPTION);
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }).start();

}

/***
 *联网注册请求
 *@return void
 *@author zmj
 *created at 2019/3/20 18:50
 */
private void requestNet(String finalStr_password_MD, String s, int option) throws IOException {


    OkHttpClient client = new OkHttpClient();
    RequestBody responseBody = null;
    if (option == Teacher_OPTION) {
        responseBody = new FormBody.Builder().add("no", str_username).add("password", finalStr_password_MD).build();
    } else if (option == Student_OPTION) {
        //Log.d("123456", "requestNet: "+123456);
        responseBody = new FormBody.Builder().add("no", str_username).add("password", finalStr_password_MD).build();
        // Log.d("responsd", responseBody.toString());
    }

    Request request = new Request.Builder().url(s).post(responseBody).build();
    Call call = client.newCall(request);
    Response response = call.execute();
    Message message = handler.obtainMessage();
    message.obj = response.body().string();
    message.arg1 = option;
    handler.sendMessage(message);
    Log.d("requestNet", (String) message.obj+message.arg1);

}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.register_btn:

            sendRequestWithOkHttp();
            break;
        case R.id.jumpToMainr: {
            Intent intent = new Intent(Register1Activity.this, LoginActivity.class);
            startActivity(intent);
            break;
        }

    }


}


@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
    flag = 0;
    switch (checkedId) {
        case R.id.teacherR:
            flag = 1;
            break;
        case R.id.studentR:
            flag = 2;
            break;
    }
}



}

（2）LoginActivity
package com.example.management;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioGroup;
import android.widget.Toast;

import com.example.management.Student.StudentHomePageActivity;


import com.example.management.Utils.StatusbarUtil;
	
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class LoginActivity extends AppCompatActivity implements View.OnClickListener, RadioGroup.OnCheckedChangeListener{


public static final int Teacher_OPTION = 1;
public static final int Student_OPTION = 2;
private String id;//获取用户id
private String str_username = "";//获取用户名
private String str_password = "";//用户密码
private String code;//服务器返回的值

private EditText accountEditl;
private EditText passwordEditl;
private Button login;

private Button jumpToRegister;
private Button back;
private RadioGroup radio_group_login;
public static int flag;


private Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        //Log.d("123456", "handleMessage: "+msg.obj.toString());
        code = jsonToJsonObject(msg.obj.toString());
        Log.d("hander", "code: "+code);
        if (code.equals("0")) {
//                MainActivity.isLogin = true;
                //保存当前信息
                Log.d("handler", "登录成功");
//                Bundle bundle = new Bundle();
//                bundle.putString("id", id);
//                bundle.putString("account", str_username);
//                bundle.putString("password", str_password);
//                bundle.putInt("option", msg.arg1);
//                bundle.putBoolean("status", true);
//                UserInfoUtil.saveCurrentInfo(getApplicationContext(), bundle);
                Toast.makeText(LoginActivity.this, "登录成功", Toast.LENGTH_SHORT).show();
                if(flag==Teacher_OPTION){
                    Intent intent1 = new Intent(LoginActivity.this, TeacherHomePageActivity.class);
                    startActivity(intent1);
                }else if(flag==Student_OPTION){
                    Intent intent = new Intent(LoginActivity.this, StudentHomePageActivity.class);
                    startActivity(intent);
                }

            //finish();
        } else if(code.equals("-1")){//若账号不存在，跳转至注册页面
            Toast.makeText(LoginActivity.this, "登录失败，请先注册", Toast.LENGTH_SHORT).show();
            accountEditl.setText("");
            passwordEditl.setText("");
            Intent intent = new Intent(LoginActivity.this, Register1Activity.class);
            startActivity(intent);
        }
        return true;
    }
});



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    StatusbarUtil.setTransparentWindow(this, false);

    initView();
}

/***
 *初始化布局
 *@param
 *@return void
 *@author
 *created at 2019/3/19 23:13
 */

private void initView() {
//        MainActivity.isLogin = false;
        accountEditl = findViewById(R.id.accountl);
        passwordEditl = findViewById(R.id.passwordl);
        login = findViewById(R.id.login_btn);
        //back = findViewById(R.id.jumpToMainl);
        radio_group_login = findViewById(R.id.radio_group_login);
        jumpToRegister = findViewById(R.id.jumpToRegister);


    login.setOnClickListener(this);
    jumpToRegister.setOnClickListener(this);
    //back.setOnClickListener(this);
    radio_group_login.setOnCheckedChangeListener(this);
}


@Override
public void onClick(View v) {

    switch (v.getId()) {
        case R.id.login_btn:
            sendRequestWithOkHttp();
            break;
        case R.id.jumpToRegister:
                Intent intent1 = new Intent(LoginActivity.this, Register1Activity.class);
                startActivity(intent1);
                break;
//            case R.id.jumpToMainl:
//                Intent intent2 = new Intent(LoginActivity.this, MainActivity.class);
//                startActivity(intent2);
//                break;
        }

    }

private void sendRequestWithOkHttp() {
    str_username = accountEditl.getText().toString();//getText()要放到监听里面
    str_password = passwordEditl.getText().toString();

    //密码进行加密
//        String str_password_MD5 = "";
//        str_password_MD5 = MD5Utils.encode(str_password);
//        final String finalStr_password_MD = str_password_MD5;

    new Thread(new Runnable() {
        @Override
        public void run() {
            //Log.d("123456", "run: " + flag);
            try {
                if (flag == Teacher_OPTION) {
                    requestNet(str_password, "http://10.161.66.7:8080/three/servlet/LoginTeacherServlet?", Teacher_OPTION);
                } else if (flag == Student_OPTION) {
                    requestNet(str_password, "http://10.161.66.7:8080/three/servlet/LoginStudentServlet?", Student_OPTION);
                    Log.d("send:  ", "http://10.161.66.7:8080/three/servlet/LoginStudentServlet?");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }).start();
}

/***
 *网络请求
 *@return void
 *@author wenhaoz
 *created at 2019/3/19 23:17
 */
private void requestNet(String finalStr_password_MD, String s, int option) throws IOException {

    OkHttpClient client = new OkHttpClient();
    RequestBody responseBody = null;
    if (option == Teacher_OPTION) {
        responseBody = new FormBody.Builder().add("no", str_username).add("password", finalStr_password_MD).build();
    } else if (option == Student_OPTION) {
        //Log.d("123456", "requestNet: "+123456);
        responseBody = new FormBody.Builder().add("no", str_username).add("password", finalStr_password_MD).build();
        // Log.d("responsd", responseBody.toString());
    }

    Request request = new Request.Builder().url(s).post(responseBody).build();
    Call call = client.newCall(request);
    Response response = call.execute();
    Message message = handler.obtainMessage();
    message.obj = response.body().string();
    message.arg1 = option;
    handler.sendMessage(message);
    Log.d("requestNet", (String) message.obj+message.arg1);
}

/***
 *解析状态码
 *@return java.lang.String
 *@author wenhaoz
 *created at 2019/3/19 23:18
 */
public String jsonToJsonObject(String json) {
    Log.d("hello", "jsonToJsonObject: " + json);
    String code = "";
    String message = null;
    try {
        JSONObject jsonObject = new JSONObject(json);
        code = jsonObject.optString("code");
        // message = jsonObject.optString("message");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return code;
}

@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {
    flag = 0;

    switch (checkedId) {
        case R.id.teacherL:
            flag = 1;
            break;
        case R.id.studentL:
            flag = 2;
            break;
    }
}
}

OK，我们继续往后看看其他代码吧~
代码有点枯燥，我们看看效果图吧~




一、Adapter包（ScoreAdapter类）

 package com.example.management;

 import android.graphics.Rect;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;

public class ItemDecoration extends RecyclerView.ItemDecoration {
private int space;

public ItemDecoration(int space) {
    this.space = space;
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    // Add top margin only for the no first item to avoid double space between items
    if (parent.getChildPosition(view) != 0) {
        outRect.left = 0;
        outRect.right = 0;
        outRect.bottom = space;
        outRect.top = 0;
    }
}

}

二、Dom包
（1）Person类）
package com.example.management.Dom;

import java.util.List;

public class Person {

/**
 * code : 0
 * data : [["1","123","1","计算机","zhao"],["2","123",null,null,null],["3","123",null,null,null],["4","123",null,null,null],["12","123",null,null,null]]
 * message : 获取所有学生信息成功！
 */

private int code;
private String message;
private List> data;

public int getCode() {
    return code;
}

public void setCode(int code) {
    this.code = code;
}

public String getMessage() {
    return message;
}

public void setMessage(String message) {
    this.message = message;
}

public List> getData() {
    return data;
}

public void setData(List> data) {
    this.data = data;
}

@Override
public String toString() {
    return "Person{" +
            "code=" + code +
            ", message='" + message + '\'' +
            ", data=" + data +
            '}';
}
}

（2）Rabbit类（当时有点匆忙，没有改名字了，这也是关于人的一个类
package com.example.management.Dom;

public class Rabbit {
/**
 * code : 0
 * data : {"cscore":0,"smajor":"计算机","sno":"1"}
 * message : 该账号存在,返回值！
 */

private int code;
private DataBean data;
private String message;

public Rabbit() {
}

public int getCode() {
    return code;
}

public void setCode(int code) {
    this.code = code;
}

public DataBean getData() {
    return data;
}

public void setData(DataBean data) {
    this.data = data;
}

public String getMessage() {
    return message;
}

public void setMessage(String message) {
    this.message = message;
}

public static class DataBean {
    /**
     * cscore : 0
     * smajor : 计算机
     * sno : 1
     */

    private int cscore;
    private String smajor;
    private String sno;

    public int getCscore() {
        return cscore;
    }

    public void setCscore(int cscore) {
        this.cscore = cscore;
    }

    public String getSmajor() {
        return smajor;
    }

    public void setSmajor(String smajor) {
        this.smajor = smajor;
    }

    public String getSno() {
        return sno;
    }

    public void setSno(String sno) {
        this.sno = sno;
    }
}
}

（3）Student类
package com.example.management.Dom;

public class Student {


private String Sno;
private String Cname;
private String Sname;
private String Sscore;
private String Smajor;
private String Cno;
public Student(){

}

public Student(String sno, String cname, String sname, String sscore, String smajor, String cno) {
    Sno = sno;
    Cname = cname;
    Sname = sname;
    Sscore = sscore;
    Smajor = smajor;
    Cno = cno;
}

public String getCno() {
    return Cno;
}

public void setCno(String cno) {
    Cno = cno;
}

public String getSno() {
    return Sno;
}

public void setSno(String sno) {
    Sno = sno;
}


public String getCname() {
    return Cname;
}

public void setCname(String cname) {
    Cname = cname;
}

public String getSscore() {
    return Sscore;
}

public void setSscore(String sscore) {
    Sscore = sscore;
}

public String getSname() {
    return Sname;
}

public void setSname(String sname) {
    Sname = sname;
}


public String getSmajor() {
    return Smajor;
}

public void setSmajor(String smajor) {
    Smajor = smajor;
}

@Override
public String toString() {
    return "Student{" +
            "Sno='" + Sno + '\'' +
            ", Cname='" + Cname + '\'' +
            ", Sname='" + Sname + '\'' +
            ", Sscore='" + Sscore + '\'' +
            ", Smajor='" + Smajor + '\'' +
            ", Cno='" + Cno + '\'' +
            '}';
}
}

（4）StudentBean类
package com.example.management.Dom;

public class StudentBean {
private String Sno;
private String Spassword;
private String Sname;
private String Cno;
private String Cscore;
private String Smajor;

public StudentBean() {

}


public StudentBean(String sno,String smajor) {
    this.Sno = sno;
    this.Smajor = smajor;
}

public StudentBean(String sno,String Spassword,String Cno,String Smajor,String Sname) {
    this.Sno = sno;
    this.Spassword = Spassword;
    this.Cno = Cno;
    this.Smajor = Smajor;
    this.Sname = Sname;
}

public StudentBean(String sno, String spassword, String sname, String cno, String cscore, String smajor) {
    Sno = sno;
    Spassword = spassword;
    Sname = sname;
    Cno = cno;
    Cscore = cscore;
    Smajor = smajor;
}

public String getSno() {
    return Sno;
}

public void setSno(String sno) {
    this.Sno = sno;
}

public String getSpassword() {
    return Spassword;
}

public void setSpassword(String spassword) {
    Spassword = spassword;
}

public String getSname() {
    return Sname;
}

public void setSname(String sname) {
    Sname = sname;
}

public String getCno() {
    return Cno;
}

public void setCno(String cno) {
    Cno = cno;
}

public String getCscore() {
    return Cscore;
}

public void setCscore(String cscore) {
    Cscore = cscore;
}

public String getSmajor() {
    return Smajor;
}

public void setSmajor(String smajor) {
    Smajor = smajor;
}
}

三、TeacherFrgment包
（1）TeacherHomeFragment类
package com.example.management.TeacherFrgment;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.management.R;


 public class TeacherHomeFragment extends Fragment {

@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.teacher_home_fragment,container,false);
    return view;
}
}

（2）TeacherMessageFragemnt类
package com.example.management.TeacherFrgment;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import com.example.management.R;

public class TeacherMessageFragemnt extends Fragment {

private ListView listView;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.teacher_message_fragment,container,false);
    return view;
}
 }

（3）TeacherScoreFragment类
package com.example.management.TeacherFrgment;

import com.example.management.AddorModifyActivity;
import com.example.management.ItemDecoration;
import com.example.management.OnRecyclerViewClickListener;
import com.example.management.R;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.DividerItemDecoration;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.ListView;

import com.alibaba.fastjson.JSON;
import com.example.management.Adapter.ScoreAdapter;
import com.example.management.Dom.Person;
import com.example.management.Dom.Student;
import com.example.management.Dom.StudentBean;
import com.example.management.R;


import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

import static android.content.ContentValues.TAG;
public class TeacherScoreFragment extends Fragment implements View.OnClickListener {

private String code;//服务器返回的值
private String data1;
private EditText textscore;
private DividerItemDecoration divider;
private ImageButton Ib_addStudentScore;

private Button btn_get;
private RecyclerView recyclerView;
private  LinearLayoutManager layoutManager;
private Person mData = null;
List> dataMessage = null;
private LinkedList mmdata = null;//展示所有学生成绩
private ScoreAdapter mAdapter = null;
private Context mContext;
private Person person;
private Toolbar toolbar_teacher_score;

private String get_Sno;
private String get_Sscore;
private String get_Sname;
private String get_Smajor;
private String get_Cname;
private String get_Cno;

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.teacher_score_fragment,container,false);
    recyclerView = view.findViewById(R.id.recycleview);


 //        recyclerView.setPadding(20, 0, 20, 0);
 //        recyclerView.addItemDecoration(new ItemDecoration(-10));

    toolbar_teacher_score = view.findViewById(R.id.toolbar_teacher_score);
    ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar_teacher_score);
    ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayShowTitleEnabled(false);//去除toolbar的title
    Ib_addStudentScore = view.findViewById(R.id.Ib_addStudentScore);


    layoutManager = new LinearLayoutManager(this.getActivity(),LinearLayoutManager.VERTICAL,false);
    //textscore = view.findViewById(R.id.textscore);
    mContext = view.getContext();
    sendRequestWithOkHttp();


    return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    Ib_addStudentScore.setOnClickListener(this);
}

private Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        //Log.d(TAG, "handleMessage: 33333333333333333333333333");
        //Log.d("123456", "handleMessage: "+msg.obj.toString());
        code = jsonToJsonObject(msg.obj.toString());
        if (code.equals("0")) {
            //finish();
        } else if(code.equals("-1")){//若账号不存在，跳转至注册页面
            textscore.setText("");
            Log.d(TAG, "handleMessage: 账号不存在");
        }
        return true;
    }
});



private void sendRequestWithOkHttp() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                requestNet( "http://10.161.66.7:8080/three/servlet/SearchScoreServlet?");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }).start();
}

/***
 *网络请求
 *@return void
 */
private void requestNet(String s) throws IOException {

    OkHttpClient client = new OkHttpClient();
    RequestBody responseBody = null;
    responseBody = new FormBody.Builder().add("no", "all").build();
    Request request = new Request.Builder().url(s).post(responseBody).build();
    Call call = client.newCall(request);
    Response response = call.execute();
    Message message = handler.obtainMessage();
    message.obj = response.body().string();
    handler.sendMessage(message);
}

public String jsonToJsonObject(String json) {
    String code =" ";
    try {
        JSONObject jsonObject = new JSONObject(json);
        code = jsonObject.optString("code");
        person =  JSON.parseObject(json,Person.class);
        dataMessage = person.getData();
        mmdata = new LinkedList();
        for(List attribute1 : dataMessage) {
            String Sno = attribute1.get(0);
            String Sscore =attribute1.get(4);
            String Cname = attribute1.get(5);
            String Smajor = attribute1.get(1);
            String Sname= attribute1.get(2);
            String Cno = attribute1.get(3);
            Student stu = new Student(Sno,Cname,Sname,Sscore,Smajor,Cno);
            Log.d(TAG, "jsonToJsonObject: stu "+stu);
            mmdata.add(stu);
            //加入分割线 161 163  164
            divider = new DividerItemDecoration(this.getActivity(),DividerItemDecoration.VERTICAL);
            mAdapter = new ScoreAdapter(mmdata,mContext);
            divider.setDrawable(ContextCompat.getDrawable(this.getActivity(),R.drawable.divider));
            recyclerView.addItemDecoration(divider);
            recyclerView.setLayoutManager(layoutManager);
            recyclerView.setAdapter(mAdapter);

            //recycleview点击item事件
            mAdapter.setItemClickListener(new OnRecyclerViewClickListener() {
                @Override
                public void onItemClickListener(View view) {
                    int position = recyclerView.getChildAdapterPosition(view);
                    List myStudent = new ArrayList<>();
                    myStudent = dataMessage.get(position);
                    Log.d(TAG, "onItemClickListener: mystudent"+myStudent.toString());
                    //Student student = new Student();
                    get_Sno = myStudent.get(0);
                    get_Sscore = myStudent.get(3);
                    get_Smajor = myStudent.get(1);
                    get_Sname = myStudent.get(2);
                    get_Cname = myStudent.get(4);
                    get_Cno = myStudent.get(5);
                    Bundle bundle = new Bundle();
                    bundle.putString("get_Sno",get_Sno);
                    bundle.putString("get_Sscore",get_Sscore);
                    bundle.putString("get_Smajor",get_Smajor);
                    bundle.putString("get_Sname",get_Sname);
                    bundle.putString("get_Cname",get_Cname);
                    bundle.putString("get_Cno",get_Cno);
                    Intent intent = new Intent(mContext,AddorModifyActivity.class);
                    intent.putExtra("Message",bundle);
                    startActivity(intent);
                }
                @Override
                public void onItemLongClickListener(View view) {

                }
            });
        }

    } catch (JSONException e) {
        e.printStackTrace();
    }
    return code;
}

@Override
public void onClick(View v) {
    switch (v.getId()){
        case R.id.Ib_addStudentScore:
            Intent intent = new Intent(getActivity(), AddorModifyActivity.class);
            startActivity(intent);
            break;
            default:break;
    }
}

 }

四、Utils包
StatusbarUtil类

package com.example.management.Utils;

import android.app.Activity;
import android.graphics.Color;
import android.os.Build;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

public class StatusbarUtil {
public static void setTransparentWindow(Activity activity, boolean flag) {
    /**
     * initialize items
     */
    /**
     * 通过设置全屏，设置状态栏透明
     *
     * @param activity
     */
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            //5.x开始需要把颜色设置透明，否则导航栏会呈现系统默认的浅灰色
            Window window = activity.getWindow();
            View decorView = window.getDecorView();
            //两个 flag 要结合使用，表示让应用的主体内容占用系统状态栏的空间
            int option = View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE;
            decorView.setSystemUiVisibility(option);
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.setStatusBarColor(Color.TRANSPARENT);
            //导航栏颜色也可以正常设置
            //window.setNavigationBarColor(Color.TRANSPARENT);
            //light mode or dark mode
            if (flag) {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
                }
            }
        } else {
            Window window = activity.getWindow();
            WindowManager.LayoutParams attributes = window.getAttributes();
            int flagTranslucentStatus = WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS;
            int flagTranslucentNavigation = WindowManager.LayoutParams.FLAG_TRANSLUCENT_NAVIGATION;
            attributes.flags |= flagTranslucentStatus;
//                attributes.flags |= flagTranslucentNavigation;
            window.setAttributes(attributes);
        }
    }
}
}

五、增查改代码（删除功能有待完善，不展示了）
（1）AddorModifyActivity
package com.example.management;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.design.widget.FloatingActionButton;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.widget.EditText;

import android.widget.ImageButton;
import android.widget.Toast;


import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.FormBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.RequestBody;
import okhttp3.Response;

public class AddorModifyActivity extends AppCompatActivity implements View.OnClickListener {

private EditText edit_Sno;
private EditText edit_Cname;
private EditText edit_Smajor;
private EditText edit_Sname;
private EditText edit_Score;
private EditText edit_Cno;

private String Sno;
private String Cname;
private String Smajor;
private String Sname;
private String code;
private String Score;
private String Cno;
private int AddStudent;
private int ModifyStudent;

private String set_Sno;
private String set_Cname;
private String set_Smajor;
private String set_Sname;
private String set_Score;
private String set_Cno;

private FloatingActionButton fab_saveStudentScore;
private FloatingActionButton fab_modifyStudentScore;
private Toolbar toolbar_add_modify;
private ImageButton Ib_backtoscore;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_addor_modify);
    edit_Sno = findViewById(R.id.edit_Sno);
    edit_Cname = findViewById(R.id.edit_Cname);
    edit_Smajor = findViewById(R.id.edit_Smajor);
    edit_Sname = findViewById(R.id.edit_Sname);
    edit_Score = findViewById(R.id.edit_Score);
    edit_Cno = findViewById(R.id.edit_Cno);
    fab_modifyStudentScore = findViewById(R.id.fab_modifyStudentScore);
    fab_saveStudentScore = findViewById(R.id.fab_saveStudentScore);
    toolbar_add_modify = findViewById(R.id.toolbar_add_modify);
    Ib_backtoscore = findViewById(R.id.Ib_backtoscore);

    fab_modifyStudentScore.setOnClickListener(this);
    fab_saveStudentScore.setOnClickListener(this);
    setSupportActionBar(toolbar_add_modify);
    Ib_backtoscore.setOnClickListener(this);

    getSupportActionBar().setDisplayShowTitleEnabled(false);//去除toolbar的title

    if(getIntent()!=null){
        Intent intent = getIntent();
        Bundle bundle = intent.getBundleExtra("Message");
        if(bundle!=null){
            set_Cname = bundle.getString("get_Cname");
            set_Sname = bundle.getString("get_Sname");
            set_Smajor = bundle.getString("get_Smajor");
            set_Sno = bundle.getString("get_Sno");
            set_Score = bundle.getString("get_Sscore");
            set_Cno = bundle.getString("get_Cno");

            edit_Sno.setText(set_Sno);
            edit_Cname.setText(set_Cname);
            edit_Smajor.setText(set_Smajor);
            edit_Sname.setText(set_Sname);
            edit_Score.setText(set_Score);
            edit_Cno.setText(set_Cno);
        }

    }


}


private Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        code = jsonToJsonObject(msg.obj.toString());
        Log.d("hander", "code: "+code);
        if (code.equals("0")) {
            if(AddStudent==1&&ModifyStudent==0){
                Toast.makeText(AddorModifyActivity.this, "增加成功", Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(AddorModifyActivity.this,TeacherHomePageActivity.class);
                startActivity(intent);
            }else if(AddStudent==0&&ModifyStudent==1){
                Toast.makeText(AddorModifyActivity.this, "修改成功", Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(AddorModifyActivity.this,TeacherHomePageActivity.class);
                startActivity(intent);
            }

            //finish();
        } else if(code.equals("-1")){//若账号不存在，跳转至注册页面
            Toast.makeText(AddorModifyActivity.this, "操作失败", Toast.LENGTH_SHORT).show();
            edit_Sno.setText("");
            edit_Cname.setText("");
            edit_Smajor.setText("");
            edit_Sname.setText("");
            edit_Score.setText("");
            edit_Cno.setText("");
            Intent intent = new Intent(AddorModifyActivity.this, TeacherHomePageActivity.class);
            startActivity(intent);
        }
        return true;
    }
});



private void sendRequestWithOkHttp() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                if(ModifyStudent==1&&AddStudent==0){
                    requestNet("http://10.161.66.7:8080/three/servlet/ModifyStudentServlet?");
                }else if(ModifyStudent==0&&AddStudent==1){
                    requestNet("http://10.161.66.7:8080/three/servlet/AddStudentScoreServlet?");
                }

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }).start();
}


private void requestNet(String s) throws IOException {
    Sno = edit_Sno.getText().toString();//getText()要放到监听里面
    Cname = edit_Cname.getText().toString();
    Smajor = edit_Smajor.getText().toString();
    Sname = edit_Sname.getText().toString();
    Score = edit_Score.getText().toString();
    Cno = edit_Cno.getText().toString();



    OkHttpClient client = new OkHttpClient();
    RequestBody responseBody = null;
    responseBody = new FormBody.Builder().add("Sno", Sno)
            .add("Cname", Cname)
            .add("Smajor", Smajor)
            .add("Sname", Sname)
            .add("Score",Score)
            .add("Cno",Cno)
            .build();
    Request request = new Request.Builder().url(s).post(responseBody).build();
    Call call = client.newCall(request);
    Response response = call.execute();
    Message message = handler.obtainMessage();
    message.obj = response.body().string();
    handler.sendMessage(message);
}


public String jsonToJsonObject(String json) {
    Log.d("hello", "jsonToJsonObject: " + json);
    String code = "";
    String message = null;
    try {
        JSONObject jsonObject = new JSONObject(json);
        code = jsonObject.optString("code");
        // message = jsonObject.optString("message");
    } catch (JSONException e) {
        e.printStackTrace();
    }
    return code;
}

@Override
public void onClick(View v) {
    switch (v.getId()){
        case R.id.fab_modifyStudentScore:
            ModifyStudent = 1;
            sendRequestWithOkHttp();
            break;
        case R.id.fab_saveStudentScore:
            AddStudent = 1;
            Log.d("onclick", "onClick: 你点击了增加");
            sendRequestWithOkHttp();
            break;
        case R.id.Ib_backtoscore:
            Intent intent = new Intent(AddorModifyActivity.this,TeacherHomePageActivity.class);
            startActivity(intent);
    }
}

 }

（2）ItemDecoration
package com.example.management;

import android.graphics.Rect;
import android.support.v7.widget.RecyclerView;
import android.view.View;

public class ItemDecoration extends RecyclerView.ItemDecoration {
    private int space;

public ItemDecoration(int space) {
    this.space = space;
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    // Add top margin only for the no first item to avoid double space between items
    if (parent.getChildPosition(view) != 0) {
        outRect.left = 0;
        outRect.right = 0;
        outRect.bottom = space;
        outRect.top = 0;
    }
}

}

（3）TeacherHomePageActivity
package com.example.management;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;


import com.example.management.TeacherFrgment.TeacherHomeFragment;
import com.example.management.TeacherFrgment.TeacherMessageFragemnt;
import com.example.management.TeacherFrgment.TeacherScoreFragment;

import java.util.ArrayList;
import java.util.List;

public class TeacherHomePageActivity extends AppCompatActivity {

private BottomNavigationView bottomNavigationView;
private int lastIndex;
List fragments;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_teacher_home_page);
    initBottomNavigation();
    initData();
    setFragmentPosition(0);
}


private void initData() {
    fragments = new ArrayList<>();
    fragments.add(new TeacherScoreFragment());
    fragments.add(new TeacherMessageFragemnt());
    fragments.add(new TeacherHomeFragment());
    setFragmentPosition(1);
}

private void setFragmentPosition(int i) {
    FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
    Fragment currentFragment = fragments.get(i);
    Fragment lastFragment = fragments.get(lastIndex);
    lastIndex= i;
    ft.hide(lastFragment);
    if(!currentFragment.isAdded()){
        getSupportFragmentManager().beginTransaction().remove(currentFragment).commit();
        ft.add(R.id.tt_frameLayout,currentFragment);
    }
    ft.show(currentFragment);
    ft.commitAllowingStateLoss();
}

public void initBottomNavigation() {
    bottomNavigationView = findViewById(R.id.bv_teacher_bottomNavigation);
    // 解决当item大于三个时，非平均布局问题
    bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {
            switch (menuItem.getItemId()) {
                case R.id.rb_scoreT:
                    setFragmentPosition(0);
                    break;
                case  R.id.rb_messageT:
                    setFragmentPosition(1);
                    break;
                case R.id.rb_homeT:
                    setFragmentPosition(2);
                    break;
                default:
                    break;
            }
            // 这里注意返回true,否则点击失效
            return true;
        }
    });
}
}

（4）MainActivity
package com.example.management;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;



import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

private static final long DELAY = 3000;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final Intent localIntent = new Intent(MainActivity.this, LoginActivity.class);
    Timer timer = new Timer();
    TimerTask task = new TimerTask() {
        @Override
        public void run() {
            startActivity(localIntent);
        }
    };
    timer.schedule(task,DELAY);
}
}

（5）OnRecyclerViewClickListener
package com.example.management;

import android.view.View;

import com.example.management.Dom.Student;

public interface OnRecyclerViewClickListener {
    void onItemClickListener(View view);
    void onItemLongClickListener(View view);
}

后台代码（展示部分）

（1）AddStudentScoreServlet类
package servlet;

import DAO.StudentDao;
import Dom.BaseBean;
import Dom.StudentBean;
import com.alibaba.fastjson.JSON;
import jdbc.DBUtilsTemplate;
import jdbc.DButils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;

@WebServlet(name = "AddStudentScoreServlet")
public class AddStudentScoreServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
    request.setCharacterEncoding("utf8");//添加，不然会中文乱码
    String Sno = request.getParameter("Sno");
    String Sname = request.getParameter("Sname");
    String Cname = request.getParameter("Cname");
    String Smajor = request.getParameter("Smajor");
    String Score = request.getParameter("Score");
    String Cno = request.getParameter("Cno");
    response.setContentType("text/html;charset=utf-8");
    int flag = 0;
    int flag2 = 0;
    String Spassword=null;
    String json = null;

    //连接数据库
    DButils dButils = new DButils();
    dButils.getConnection();
    BaseBean data = new BaseBean();
    StudentBean studentBean = new StudentBean();

    if(Sno==null||Sno.equals("")){
        data.setCode(-1);
        data.setData(studentBean);
        data.setMessage("该账号存在,插入失败");
    }else{
        int flag1 = dButils.isStudentExecstByTeacher(Sno);
        if(flag1 == 1){
            System.out.println("失败");
            data.setCode(-1);
            data.setData(studentBean);
            data.setMessage("该账号存在,插入失败");
        }else{
            try{
                StudentDao studentDao = new StudentDao();
                flag = studentDao.saveStudentScore(Sno,"123",Cno,Smajor,Sname);
                flag2 = studentDao.ModifyStudentScore2(Cno,Sno,Score,Cname);
                if(flag ==1&&flag2==1){
                    data.setCode(0);
                    data.setData(studentBean);
                    data.setMessage("增加成功");
                }else{
                    data.setCode(-2);
                    data.setData(studentBean);
                    data.setMessage("系统繁忙，稍后重试");
                }
            }catch (SQLException e){
                e.printStackTrace();
            }
        }

        json = JSON.toJSONString(data);
        System.out.println(json);
    }


    try{
        response.getWriter().println(json);
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        response.getWriter().close();
    }
    dButils.disConnection();
}
}

（2）ModifyStudentServlet类
package servlet;

import DAO.StudentDao;
import Dom.BaseBean;
import Dom.StudentBean;
import com.alibaba.fastjson.JSON;
import jdbc.DButils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.SQLException;

@WebServlet(name = "ModifyStudentServlet")
public class ModifyStudentServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           doGet(request,response);
    }

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf8");//添加，不然会中文乱码
    String Sno = request.getParameter("Sno");
    String Sname = request.getParameter("Sname");
    String Smajor = request.getParameter("Smajor");
    String Cname = request.getParameter("Cname");
    String Score = request.getParameter("Score");
    String Cno = request.getParameter("Cno");
    int flag2 = 0;
    int flag = 0;
    response.setContentType("text/html;charset=utf-8");
    String Spassword=null;

    //连接数据库
    DButils dButils = new DButils();
    dButils.getConnection();
    BaseBean data = new BaseBean();
    StudentBean studentBean = new StudentBean();
    int flag1 = dButils.isStudentExecstByTeacher(Sno);//判断学号是否存在
    System.out.println(flag1+"   =====flag1");
    if(flag1 == 1){
        try{
            StudentDao studentDao = new StudentDao();
            flag = studentDao.ModifyStudentScore(Sno,Spassword,Cno,Smajor,Sname);
            flag2 = studentDao.saveStudentScore2(Cno,Sno,Score,Cname);
            System.out.println("flga  ===="+flag);
            if(flag ==1){
                System.out.println("修改成功");
                data.setCode(0);
                data.setData(studentBean);
                data.setMessage("修改成功");
            }else{
                System.out.println("修改失败");
                data.setCode(-2);
                data.setData(studentBean);
                data.setMessage("系统繁忙，稍后重试");
            }
        }catch (SQLException e){
            e.printStackTrace();
        }
    }else{
        data.setCode(-1);
        data.setData(studentBean);
        data.setMessage("该账号不存在,修改失败");
    }

    String json = JSON.toJSONString(data);
    System.out.println(json);
    try{
        response.getWriter().println(json);
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        response.getWriter().close();
    }
    dButils.disConnection();
}
}

（3）RegisterTeacherServlet类
package servlet;

import Dom.BaseBean;
import Dom.TeacherBean;
import com.alibaba.fastjson.JSON;
import jdbc.DButils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(name = "RegisterTeacherServlet")
public class RegisterTeacherServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          doGet(request,response);
    }

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       request.setCharacterEncoding("utf8");//添加，不然会中文乱码
      String Tno = request.getParameter("no");
      String Tpassword = request.getParameter("password");
      System.out.println("教师号: "+Tno);
       System.out.println("教师密码: "+Tpassword);
      response.setContentType("text/html;charset=utf-8");
      if(Tno.length()>10||Tno==null||Tpassword==null||Tpassword.equals("")){
          System.out.println("用户名长度不对或者密码为空");
          return;
      }

      DButils dButils = new DButils();
      dButils.getConnection();
      BaseBean data = new BaseBean();
      TeacherBean teacherBean = new TeacherBean();

    if(dButils.isTeacherExecstInDB(Tno,Tpassword)==1){//用户账号存在（失败）
        data.setCode(-1);
        data.setData(teacherBean);
        data.setMessage("账号存在，请先重新注册！");
        //System.out.println("账号账号存在，请先重新注册");
    }else if(dButils.isTeacherExecstInDB(Tno,Tpassword)==0){
        boolean flag = dButils.insertTeacherDB(Tno,Tpassword);
        if(!flag){
            data.setCode(0);
            data.setData(teacherBean);
            data.setMessage("注册成功！");
        }else{
            data.setCode(-2);
            data.setData(teacherBean);
            data.setMessage("系统繁忙，稍后重试！");
        }

    }
    String json = JSON.toJSONString(data);
    try{
        response.getWriter().println(json);
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        response.getWriter().close();
    }
    dButils.disConnection();
}
}

（4）SearchScoreServlet类
package servlet;

import DAO.StudentDao;
import Dom.BaseBean;
import Dom.StudentBean;
import com.alibaba.fastjson.JSON;
import javafx.beans.binding.ObjectExpression;
import jdbc.DButils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.bind.ValidationException;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Vector;

@WebServlet(name = "SearchScoreServlet")
public class SearchScoreServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    doGet(request,response);
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("utf8");//添加，不然会中文乱码
    String Sno = request.getParameter("no");

    response.setContentType("text/html;charset=utf-8");

    System.out.println(Sno);
    //连接数据库

    DButils dButils = new DButils();
    dButils.getConnection();
    BaseBean data = new BaseBean();
    StudentDao studentDao = new StudentDao();

    Vector> studentBean= new Vector<>();

    if(Sno.equals("all")){
        try {
            studentBean = studentDao.queryStudentBean("select DISTINCT s.sno,s.smajor,s.sname,c.cno,c.cscore,c.cname \n" +
                    "from student as s LEFT join course as c \n" +
                    "on s.sno=c.sno and s.cno=c.cno\n ",new Object[]{"Sno","Smajor","Sname","Cscore","Cname","Cno"});
            System.out.println(studentBean);
            if(studentBean!=null){
                data.setCode(0);
                data.setData(studentBean);
                data.setMessage("获取所有学生信息成功！");
            }else{
                data.setCode(0);
                data.setData(studentBean);
                data.setMessage("获取所有学生信息失败！");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }else{
        System.out.println("单个查询"+Sno);
        try {
            studentBean = studentDao.searchStudentBean("select DISTINCT s.sno,s.smajor,s.sname,c.cno,c.cscore,c.cname \n" +
                    "from student as s LEFT join course as c \n" +
                    "on s.sno=c.sno and s.cno=c.cno\n",new Object[]{"Sno","Smajor","Sname","Cscore","Cname","Cno"},Sno);
            System.out.println(studentBean);
            if(studentBean!=null){
                data.setCode(0);
                data.setData(studentBean);
                data.setMessage("获取学生信息成功！");
            }else{
                data.setCode(0);
                data.setData(studentBean);
                data.setMessage("获取学生信息失败！");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    System.out.println("打印studentBean： "+studentBean);
    String json = JSON.toJSONString(data);
    System.out.println(json);
    try{
        response.getWriter().println(json);
    }catch (Exception e){
        e.printStackTrace();
    }finally {
        response.getWriter().close();
    }
    dButils.disConnection();
}
}

小白，有好多地方可以改进，请多多指教~
想要完整代码和，可以私我~