android之JSON 进行网络数据交换

什么是JSON

“ abc ”，其格式为："abc"。除了字符 "，\，/ 和一些控制符（\b，\f，\n，\r，\t）需要编码外，其他 Unicode 字符可以直接输出。

       Boolean 类型表示为 true 或 false 。此外，JavaScript 中的 null 被表示为 null，注意，true、false和 null 都没有双引号，否则将被视为一个 String 。

JSON 还可以表示一个数组对象，使用 [] 包含所有元素，每个元素用逗号分隔，元素可以是任意的
Value，例如，以下数组包含了一个 String，Number，Boolean 和一个 null：

["abc",12345,false,null]

{"city":"Beijing","street":" Chaoyang Road ","postcode":100025}

{"name":"Michael","address":
 {"city":"Beijing","street":" Chaoyang Road ","postcode":100025}

 }

下面写一个实例：（记得服务器端要先导包）

     这是在我曾经写好的代码上写的，我现在把主要代码写下。

     新建一个servlet：

package cn.four.json;

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

import javax.print.event.PrintServiceAttributeEvent;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import cn.four.service.Foundservice;
import cn.four.service.FoundserviceImp;
import cn.four.user.Found;



public class JSONDemoServlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		Foundservice fd=new FoundserviceImp();   //我这是以前写过的，继承接口
		
		List<Found> list=fd.getfound();       //new 一个list
		JSONObject jsb=new JSONObject();      //new 一个JSONObject对象
		
		jsb.put("foundlist",list);           //得到转成后的数据
		
		JSONArray fdarray=jsb.getJSONArray("foundlist");     //存到数组
		
		response.setContentType("text/plain");//解决乱码
		response.setCharacterEncoding("UTF-8");
		PrintWriter out=response.getWriter();
		 out.write(fdarray.toString());   //关闭
		 out.flush();
		 out.close();
		
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		
	}

}

下面是android的介绍

         Android SDK 提供了Apache 的HttpClient 类处理网络访问，相信很多读者朋友都在其他项目当中用
到过HttpClient。我写了一个方法类，获取某一网址的网页内容，代码如下：

package com.four.http;

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;

public class httpcontent {
	
	public 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) {
			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();
}

}

package com.example.mychat;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.SimpleAdapter;

import com.four.http.httpcontent;

public class User_tips extends Activity {

	httpcontent content = new httpcontent();
	private Button btnshua;
	private ListView xianshi;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_user_tips);
		btnshua = (Button) findViewById(R.id.btnshua);
		xianshi = (ListView) findViewById(R.id.listView1);
		btnshua.setOnClickListener(new shualistener());

	}

	class shualistener implements OnClickListener {

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub		
			listxianshi();
		}

	}

	private List<Map<String, Object>> getmessg(String url) {
		List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
		String body;
		try {
			body = content.getContent(url);
			JSONArray array = new JSONArray(body);
			for (int i = 0; i < array.length(); i++) {
				JSONObject obj = array.getJSONObject(i);
				Map<String, Object> map = new HashMap<String, Object>();
				map.put("foundname", obj.getString("foundname"));
				map.put("foundplace", obj.getString("foundplace"));
				list.add(map);
			}

		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return list;
	}

	private void listxianshi(){
		try {
			String url = "http://10.20.180.34:8080/lostfound/JSONDemoServlet";
			SimpleAdapter adapter = new SimpleAdapter(this,
					getmessg(url), R.layout.list_item, new String[] {
							"foundname", "username" }, new int[] {
							R.id.foundname, R.id.username });
			xianshi.setAdapter(adapter);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

效果图：

android之JSON 进行网络数据交换,布布扣,bubuko.com

android之JSON 进行网络数据交换

原文：http://blog.csdn.net/u013007955/article/details/38750795