Android[中級教程]第八章 Json資料的處理

 經過上幾章的學習,相信同學們對XML解析已經得心應手了,但今天我們要解析Json資料,因為Json資料佔用資料量小,因此在Android中主要資料通訊還是以Json為主,而且Json資料可以跟Android進行AJAX互動,相當方便哦,好了,不多說了,看圖跟代碼:

先:

首先定義了Json資料:

{ "persons": [ { "id": "1", "status":"大徙弟", "name": "孫悟空", "tool": "金箍棒", "number": "殺死了50隻妖怪" }, { "id": "2", "status":"二徙弟", "name": "豬八戒", "tool": "九齒釘耙", "number": "殺死了43隻妖怪" },{ "id": "3", "status":"三徙弟", "name": "沙和尚", "tool": "降妖寶杖", "number": "殺死了33隻妖怪" }]} 

接下來就是定義javaBean了,對於java開發來說,javaBean可以很方便地儲存和管理資料

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;}@Overridepublic String toString(){return "Person [id=" + id + ", status=" + status + ", name=" + name+ ", tool=" + tool + ", number=" + number + "]";}}

 

接下來就是 Json的處理了,定義了一個JsonHandler類

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{//自訂方法,從輸入資料流中取得字串String json_str = getJsonString(input);//通過字串產生Json對象JSONObject object = new JSONObject(json_str);//將Json對象中的persons資料轉換成Json數組JSONArray array = object.getJSONArray("persons");//數組長度int length = array.length();for (int i = 0; i < length; i++){//將每一個數組再轉換成Json對象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;}/** * 將輸入資料流中資料整合成字串 *  * @param input *            輸入資料流 * @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,到這裡資料應該能解析出來了,可以通過測試類別來測試一下,呵呵,我還是比較喜歡邊測試邊做下一步開發

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(){// 取得當前SD目錄下的檔案路徑File SD_Files = Environment.getExternalStorageDirectory();// 取得persons.xml檔案的路徑,這裡我是存在sdcard/data.jsonString 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,測試沒問題了,那我們就上主Activity類了

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;@Overrideprotected void onCreate(Bundle savedInstanceState){// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.xml_handler);listView = (ListView) findViewById(R.id.xml_list);try{// 自完義適配方法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卡目錄File SD_Files = Environment.getExternalStorageDirectory();//取得檔案路徑String file_path = SD_Files.getName() + File.separator + "data.json";//Json處理FileInputStream fis = new FileInputStream(new File(file_path));JsonHandler jsonHandler = new JsonHandler(fis);List<Person> persons = jsonHandler.getPersons();// 將persons中的資料轉換到ArrayList<Map<String,String>>中// String>>中,因為SimpleAdapter要用這個類型的資料進行適配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keyString[] from = { "id", "status", "name", "tool", "number" };// list_item.xml中對應的控制項IDint[] 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);}}

這裡面還定義了幾個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="唐僧的三個徙弟"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的資料處理我們也學習完了.

源碼下載