Json入门

参考《疯狂android讲义》》730页

JSON的基础请参考W3SCHOOL的教程：

http://www.w3school.com.cn/json/index.asp

例子：

http://wenku.baidu.com/link?url=A5SiKBUNVx-aB_hFiDuHsEN1uw_Vu4a9ODRq7G-SpiY-qW11Ve8Ba8ym9TfheAUuHJhYgdD3g05lvGNWrPBzf7JZFhUlAcZYb0MMIdrcmp3

1、创建服务器端：

（1）创建对象类

package com.ljh.jsondemo.model;

public class User {
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getGender() {
		return gender;
	}
	public void setGender(String gender) {
		this.gender = gender;
	}
	private int id;
	private String name;
	private String email;
	private String gender;  
}

（2）创建json的提供类

package com.ljh.jsondemo.servlet;

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

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

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

import com.ljh.jsondemo.model.User;

public class JsonDemoServlet extends HttpServlet {

	private static final long serialVersionUID = -7368225680407826408L;

	private List<User> list;

	/** * 处理post方式提交的数据 */

	public void doPost(HttpServletRequest request, HttpServletResponse response)

	throws ServletException, IOException {
		doGet(request, response);

	}

	/** * 处理get方式提交的数据 */

	public void doGet(HttpServletRequest request, HttpServletResponse response)

	throws ServletException, IOException {

		response.setContentType("text/plain");

		response.setCharacterEncoding("UTF-8");

		PrintWriter out = response.getWriter();

		// 准备用户数据

		prepareData();

		// JSON数组

		JSONArray array = new JSONArray();

		for (User bean : list) {

			// 单个用户JSON对象

			JSONObject obj = new JSONObject();

			try {
				obj.put("id", bean.getId());

				obj.put("name", bean.getName());

				obj.put("email", bean.getEmail());

				obj.put("gender", bean.getGender());

			}

			catch (Exception e) {
			}

			array.put(obj);

		}

		// 输出

		out.write(array.toString());

		out.flush();
		out.close();
	}

	private void prepareData() {

		list = new ArrayList<User>();

		User bean1 = new User();

		bean1.setId(1001);

		bean1.setName("Tony");

		bean1.setEmail("");

		bean1.setGender("male");

		list.add(bean1);

		User bean2 = new User();

		bean2.setId(1002);

		bean2.setName("Jack");

		bean2.setEmail("");

		bean2.setGender("male");

		list.add(bean2);

		User bean3 = new User();

		bean3.setId(1003);

		bean3.setName("Marry");

		bean3.setEmail("");

		bean3.setGender("female");

		list.add(bean3);

		User bean4 = new User();

		bean4.setId(1004);

		bean4.setName("Linda");

		bean4.setEmail("");

		bean4.setGender("female");

		list.add(bean4);

	}

}

2、创建android客户端

注意要添加访问internet的权限。

package com.ljh.jsondemoclient;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.json.JSONArray;
import org.json.JSONObject;

import android.os.Bundle;
import android.app.Activity;
import android.widget.TextView;

public class MainActivity extends Activity {

	

	private String getContent(String url) throws Exception {

		StringBuilder sb = new StringBuilder();

		HttpClient client = new DefaultHttpClient();

		HttpParams httpParams = client.getParams();

		// 设置网络超时参数

		HttpConnectionParams.setConnectionTimeout(httpParams, 3000);

		HttpConnectionParams.setSoTimeout(httpParams, 5000);

		HttpResponse response = client.execute(new HttpGet(url));

		HttpEntity entity = response.getEntity();

		if (entity != null) {
			System.out.println("test!!!!");

			BufferedReader reader = new BufferedReader(new InputStreamReader(
					entity.getContent(), "UTF-8"), 8192);

			String line = null;

			while ((line = reader.readLine()) != null) {

				sb.append(line + "\n");

			}

			reader.close();

		}
		return sb.toString();

	}

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

		try {

			StringBuffer sb = new StringBuffer();

			// 在测试过程中，经常是用本机做测试服务器，访问本机的IP地址要设置为10.0.2.2

			String url = "192.168.136.133:8080/JsonDemoServer/JsonDemoServlet";

			String body = getContent(url);

			JSONArray array = new JSONArray(body);

			for (int i = 0; i < array.length(); i++) {

				JSONObject obj = array.getJSONObject(i);

				sb.append("id:").append(obj.getInt("id")).append("\t");

				sb.append("name:").append(obj.getString("name")).append("\r\n");

				sb.append("gender:").append(obj.getString("gender"))
						.append("\t");

				sb.append("email:").append(obj.getString("email"))
						.append("\r\n");

				sb.append("----------------------\r\n");

			}

			TextView textView = (TextView) findViewById(R.id.tv_json_content);

			textView.setText(sb.toString());

		} catch (Exception e) {
		}
	}
}