Android[中级教程]第八章 Json数据的处理

 

Android[中级教程]第八章 Json数据的处理

分类： Android中级 2011-10-08 00:29  727人阅读  评论(2)  收藏  举报

 经过上几章的学习,相信同学们对XML解析已经得心应手了,但今天我们要解析Json数据,因为Json数据占用数据量小,因此在Android中主要数据通信还是以Json为主,而且Json数据可以跟Android进行AJAX互动,相当方便哦,好了,不多说了,看图跟代码:

先上图:

首先定义了Json数据:

 { "persons": [
 { "id": "1", "status":"大徙弟", "name": "孙悟空", "tool": "金箍棒", "number": "杀死了50只妖怪" },
 { "id": "2", "status":"二徙弟", "name": "猪八戒", "tool": "九齿钉耙", "number": "杀死了43只妖怪" },
 { "id": "3", "status":"三徙弟", "name": "沙和尚", "tool": "降妖宝杖", "number": "杀死了33只妖怪" }
 ]}

接下来就是定义javaBean了,对于java开发来说,javaBean可以很方便地存储和管理数据

 public class Person
 {
     private String id;
     private String status;
     private String name;
     private String tool;
     private String number;


     public String getId()
     {
         return id;
     }
     public void setId(String id)
     {
         this.id = id;
     }
     public String getStatus()
     {
         return status;
     }
     public void setStatus(String status)
     {
         this.status = status;
     }
     public String getName()
     {
         return name;
     }
     public void setName(String name)
     {
         this.name = name;
     }
     public String getTool()
     {
         return tool;
     }
     public void setTool(String tool)
     {
         this.tool = tool;
     }
     public String getNumber()
     {
         return number;
     }
     public void setNumber(String number)
     {
         this.number = number;
     }
     @Override
     public String toString()
     {
         return "Person [id=" + id + ", status=" + status + ", name=" + name
                 + ", tool=" + tool + ", number=" + number + "]";
     }

 }

 

接下来就是 Json的处理了,定义了一个JsonHandler类

 import java.io.BufferedReader;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 import java.util.List;

 import org.json.JSONArray;
 import org.json.JSONObject;

 public class JsonHandler
 {
     private InputStream input;
     private List<Person> persons;
     private Person person;

     public JsonHandler()
     {
     }

     public JsonHandler(InputStream input)
     {
         this.input = input;
     }

     public void setInput(InputStream input)
     {
         this.input = input;
     }

     public List<Person> getPersons()
     {
         persons = new ArrayList<Person>();
         try
         {
             //自定义方法,从输入流中取得字符串
             String json_str = getJsonString(input);
             //通过字符串生成Json对象
             JSONObject object = new JSONObject(json_str);
             //将Json对象中的persons数据转换成Json数组
             JSONArray array = object.getJSONArray("persons");
             //数组长度
             int length = array.length();
             for (int i = 0; i < length; i++)
             {
                 //将每一个数组再转换成Json对象
                 JSONObject obj = array.getJSONObject(i);

                 person = new Person();
                 person.setId(obj.getString("id"));
                 person.setStatus(obj.getString("status"));
                 person.setName(obj.getString("name"));
                 person.setTool(obj.getString("tool"));
                 person.setNumber(obj.getString("number"));

                 persons.add(person);

             }

             return persons;

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

         return null;
     }

     /**
      * 将输入流中数据整合成字符串
      *
      * @param input
      *            输入流
      * @return
      * @throws Exception
      */
     private String getJsonString(InputStream input) throws Exception
     {
         BufferedReader reader = new BufferedReader(new InputStreamReader(input));
         StringBuilder sb = new StringBuilder();
         for (String s = reader.readLine(); s != null; s = reader.readLine())
         {
             sb.append(s);
         }

         return sb.toString();
     }

 }

OK,到这里数据应该能解析出来了,可以通过测试类来测试一下,呵呵,我还是比较喜欢边测试边做下一步开发

 import java.io.File;
 import java.io.FileInputStream;

 import java.util.List;

 import android.os.Environment;
 import android.test.AndroidTestCase;

 public class HandlerTest extends AndroidTestCase
 {


     public void testJsonGetPersons()
     {

         // 取得当前SD目录下的文件路径
         File SD_Files = Environment.getExternalStorageDirectory();
         // 取得persons.xml文件的路径,这里我是存在sdcard/data.json
         String file_path = SD_Files.getName() + File.separator + "data.json";

         try
         {
             FileInputStream fis = new FileInputStream(new File(file_path));
             JsonHandler jsonHandler = new JsonHandler(fis);
             List<Person> persons = jsonHandler.getPersons();
             System.out.println(persons);

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

     }
 }

好,测试没问题了,那我们就上主Activity类了

 import java.io.File;
 import java.io.FileInputStream;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;

 import android.app.Activity;
 import android.os.Bundle;
 import android.os.Environment;
 import android.widget.ListView;
 import android.widget.SimpleAdapter;

 public class JsonActivity extends Activity
 {
     private ListView listView;
     private SimpleAdapter adapter;

     @Override
     protected void onCreate(Bundle savedInstanceState)
     {
         // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);
         setContentView(R.layout.xml_handler);

         listView = (ListView) findViewById(R.id.xml_list);
         try
         {
             // 自完义适配方法
             getAdapter();

         } catch (Exception e)
         {
             e.printStackTrace();
         }
         listView.setAdapter(adapter);
     }

     private void getAdapter() throws Exception
     {
         List<Map<String, String>> lists = new ArrayList<Map<String, String>>();
         //取得SD卡目录
         File SD_Files = Environment.getExternalStorageDirectory();
         //取得文件路径
         String file_path = SD_Files.getName() + File.separator + "data.json";
         //Json处理
         FileInputStream fis = new FileInputStream(new File(file_path));
         JsonHandler jsonHandler = new JsonHandler(fis);
         List<Person> persons = jsonHandler.getPersons();

         // 将persons中的数据转换到ArrayList<Map<String,String>>中
         // String>>中,因为SimpleAdapter要用这个类型的数据进行适配
         Map<String, String> map;
         for (Person p : persons)
         {
             map = new HashMap<String, String>();

             map.put("id", p.getId());
             map.put("status", p.getStatus());
             map.put("name", p.getName());
             map.put("tool", p.getTool());
             map.put("number", p.getNumber());

             lists.add(map);
         }

         // HashMap<String, String>中的key
         String[] from = { "id", "status", "name", "tool", "number" };
         // list_item.xml中对应的控件ID
         int[] to = { R.id.item_id, R.id.item_status, R.id.item_name,
                 R.id.item_tool, R.id.item_number };

         adapter = new SimpleAdapter(this, lists, R.layout.handler_list_item,
                 from, to);
     }

 }

这里面还定义了几个Layout,也一起送上吧:

xml_handler.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical" android:layout_width="match_parent"
     android:layout_height="match_parent">
     <TextView android:textAppearance="?android:attr/textAppearanceMedium"
         android:layout_width="wrap_content" android:text="唐僧的三个徙弟"
         android:layout_height="wrap_content" android:id="@+id/textView1"
         android:paddingLeft="10dip" android:paddingBottom="10dip"></TextView>
     <ListView android:id="@+id/xml_list" android:layout_height="wrap_content"
         android:layout_width="match_parent"></ListView>

 </LinearLayout>

handler_list_item.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical" android:layout_width="match_parent"
     android:layout_height="match_parent" android:paddingLeft="10dip"
     android:paddingRight="10dip">
     <LinearLayout android:id="@+id/linearLayout1"
         android:layout_height="wrap_content" android:layout_width="match_parent">
         <TextView android:textAppearance="?android:attr/textAppearanceMedium"
             android:layout_width="wrap_content" android:text="TextView"
             android:layout_height="wrap_content" android:id="@+id/item_id" android:paddingRight="30dip"></TextView>
         <TextView android:textAppearance="?android:attr/textAppearanceMedium"
             android:layout_width="wrap_content" android:text="TextView"
             android:layout_height="wrap_content" android:id="@+id/item_status" android:paddingRight="30dip"></TextView>
         <TextView android:textAppearance="?android:attr/textAppearanceMedium"
             android:layout_width="wrap_content" android:text="TextView"
             android:layout_height="wrap_content" android:id="@+id/item_name"></TextView>
     </LinearLayout>
     <LinearLayout android:id="@+id/linearLayout2"
         android:layout_height="wrap_content" android:layout_width="match_parent">
         <TextView android:textAppearance="?android:attr/textAppearanceMedium"
             android:layout_width="wrap_content" android:text="TextView"
             android:layout_height="wrap_content" android:id="@+id/item_tool" android:paddingRight="30dip"></TextView>
         <TextView android:textAppearance="?android:attr/textAppearanceMedium"
             android:layout_width="wrap_content" android:text="TextView"
             android:layout_height="wrap_content" android:id="@+id/item_number"></TextView>
     </LinearLayout>

 </LinearLayout>

好了,Json的数据处理我们也学习完了.

因为找不到比较好的文件服务器,如果哪位同学想要源码的,可以留邮件地址,谢谢