Servlet和Android网络交互基础_MVP（2）

    在第一章中我们实现了最基本的Servlet和Android用get进行网络交互功能。在实际开发中基本是需要带参数的，需要处理get/post，head，cookie，parameter等等；还要进行业务处理，访问数据库，组装数据。然后才会下发数据到客户端。
    在这里面因为代码的业务越来越复杂，版本迭代等因素造成Servlet的代码也会越来越多，IT人员的高度流动性加剧了代码维护工作量，甚至到后期就是灾难性的。下面我们用MVP来降低代码的耦和型，在Server端因为没有View层可以叫SVP。在这里不在介绍MVP的思想了，直接代码实现

Servlet实现

Presenter 部分

FirstPresenter处理数据解析和业务逻辑调度，代码如下

package servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FirstPresenter implements FirstPresenterInterface {
    private FirstServletInterface mFirstServletInterface;
    public FirstPresenter(FirstServletInterface servletInterface){
        mFirstServletInterface = servletInterface;
    }
    public void parseParameters(HttpServletRequest request,
            HttpServletResponse response,int type) {
        // TODO Auto-generated method stub
        System.out.println("处理请求类型。。。type="+type);
        response.setContentType("text/html;charset=utf-8");
        String sendMsg = "这是来自FirstServlet的数据";
        mFirstServletInterface.sendMSG(response,sendMsg);
    }
}

FirstPresenterInterface把FirstPresenter方法暴露给Servlet，Servlet只能访问暴露的方法。代码如下

package servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public interface FirstPresenterInterface {
    public void parseParameters(HttpServletRequest request, HttpServletResponse response,int httpType);
}

Server 部分

FirstServlet接收和下发数据，不在进行任何的业务处理。代码如下

package servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FirstServlet extends HttpServlet implements FirstServletInterface{

    FirstPresenterInterface mPresenter;
    /** * Constructor of the object. */
    public FirstServlet() {
        super();
    }

    /** * Destruction of the servlet. <br> */
    public void destroy() {
        super.destroy(); // Just puts "destroy" string in log
        // Put your code here
    }

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
// super.doDelete(req, resp);
        System.out.println("处理Get请求。。。");

        mPresenter.parseParameters(request, response, HttpType.HTTP_TYPE_GET);
// response.setContentType("text/html;charset=utf-8");
// PrintWriter out = response.getWriter();
// 
// out.println("<strong>Hello servlet</strong>");
// out.flush();
// out.close();
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
// super.doGet(request, response);
        System.out.println("处理Post请求。。。");
        mPresenter.parseParameters(request, response, HttpType.HTTP_TYPE_POST);
// response.setContentType("text/html;charset=utf-8");
// PrintWriter out = response.getWriter();
// 
// out.println("<strong>Hello servlet</strong>");
// out.flush();
// out.close();
    }
    /** * Initialization of the servlet. <br> * * @throws ServletException if an error occurs */
    public void init() throws ServletException {
        // Put your code here
        mPresenter = new FirstPresenter(this);
    }

    public void sendMSG(HttpServletResponse response,String msg) {

        PrintWriter out;
        try {
            out = response.getWriter();
            out.println(msg);
            out.flush();
            out.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

FirstServletInterface P层处理完业务逻辑后调度接口定义的方法,这里传递response和P生成的数据msg

package servlet;

import javax.servlet.http.HttpServletResponse;

public interface FirstServletInterface {
    public void sendMSG(HttpServletResponse response,String msg);
}

Module部分

数据模块，因我们的比较简单还没有牵扯到数据库，这里暂时空着。具体实现实在P解析数据以后，根据业务逻辑和module交互，获取资源在传递到S层

HttpType常量定义

package servlet;

public class HttpType {
    public static final int HTTP_TYPE_GET = 0;
    public static final int HTTP_TYPE_POST = 1;
}

Android实现

和上面服务端一样，移动的项目因为UI修改、版本迭代、技术更新、人员离职、机型适配等等造成项目也是越来越难维护。如果中间有错误实现，到后期调试会非常的浪费时间。下面是本例子android代码

Presenter 部分

MainPresenter 不在直接接触UI，当然也不能做Activity里面页面跳转逻辑，仅仅处理业务。

package com.example.zqw.servletdemo;

import android.util.Log;

import com.zhy.http.okhttp.OkHttpUtils;
import com.zhy.http.okhttp.callback.StringCallback;

import okhttp3.Call;
import okhttp3.Request;

/** * Created by zqw on 2016/2/24. */
public class MainPresenter implements PresenterInterface{
    MainInterface mInterface;
    public MainPresenter(MainInterface mainInterface){
        this.mInterface = mainInterface;
    }


    @Override
    public void getInfo() {
        String url = "http://172.16.41.113:8080/FirstServletDemo/servlet/HelloServlet";
        OkHttpUtils
                .get()
                .url(url)
                .build()
                .execute(new MyStringCallback());
    }


    public class MyStringCallback extends StringCallback {
        @Override
        public void onBefore(Request request)
        {
            super.onBefore(request);
// setTitle("loading...");
        }

        @Override
        public void onAfter()
        {
            super.onAfter();
// setTitle("Sample-okHttp");
        }

        @Override
        public void onError(Call call, Exception e)
        {
            mInterface.showErrorInfo("您的请求出错啦："+e.toString());
        }

        @Override
        public void onResponse(String response)
        {
            mInterface.showErrorInfo("您获取的数据是:"+response);
        }

        @Override
        public void inProgress(float progress)
        {
         // Log.e(TAG, "inProgress:" + progress);
        }
    }

}

View 部分

MainActivity不在处理网络请求，这里只关心view相关工作。继承MainInterface并实现二个方法，显示正常请求数据和请求异常的提示

package com.example.zqw.servletdemo;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
import android.widget.Toast;

import com.zhy.http.okhttp.OkHttpUtils;
import com.zhy.http.okhttp.callback.StringCallback;

import okhttp3.Call;
import okhttp3.Request;

public class MainActivity extends AppCompatActivity implements MainInterface{
    private static final String TAG = "MainActivity";
    TextView mTV;
    MainPresenter mainPresenter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTV = (TextView)findViewById(R.id.servletTV);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });
        mainPresenter = new MainPresenter(this);
        mainPresenter.getInfo();
    }


    public void showInfo(String msg) {
        mTV.setText(msg);
    }

    public void showErrorInfo(String msg) {
        mTV.setText(msg);
        Toast toast = Toast.makeText(this,msg,Toast.LENGTH_LONG);
        toast.show();
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}