Android 调用WebAPI

1)准备工作
gson的下载地址如下
http://www.java2s.com/Code/Jar/g/gson.htm

下载后如何调用，这个问题对Android高手是多余的，但是很多新手应该还是需要讲解一下的

首先我们将gson-2.1.jar粘贴到项目的“libs”目录下，然后点击Eclipse的"Project"下的“Properties”选项卡，接下来选择左边的“Java Build Path”后在右边选择“Libraries”选项卡，单机“Add JARs...”按钮通过浏览到当前项目下的"libs"目录将gson-2.1添加。

2)创建类StudentInfo.java代码如下（类名和字段和WebAPI端保持一致）

package com.example.webapitest;public class StudentInfo {private int stuId;private String stuName;private String stuAddress;public int getStuId() {return stuId;}public void setStuId(int stuId) {this.stuId = stuId;}public String getStuName() {return stuName;}public void setStuName(String stuName) {this.stuName = stuName;}public String getStuAddress() {return stuAddress;}public void setStuAddress(String stuAddress) {this.stuAddress = stuAddress;}public static final String STUDENT_NAME = "stuName";    public static final String STUDENT_ADDRESS = "stuAddress";}

3）创建调用WebAPI类JSONHttpClient代码如下

package com.example.webapitest;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.UnsupportedEncodingException;import java.util.List;import java.util.zip.GZIPInputStream;import org.apache.http.Header;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.HttpStatus;import org.apache.http.NameValuePair;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.methods.HttpDelete;import org.apache.http.client.methods.HttpGet;import org.apache.http.client.methods.HttpPost;import org.apache.http.client.methods.HttpPut;import org.apache.http.client.utils.URLEncodedUtils;import org.apache.http.entity.StringEntity;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.params.CoreConnectionPNames;import com.google.gson.GsonBuilder;public class JSONHttpClient {private int timeOut=5000;//超时时间//UPDATEpublic <T> T PutObject(String url, final T object, final Class<T> objectClass){        DefaultHttpClient defaultHttpClient = new DefaultHttpClient();        HttpPut httpPut=new HttpPut(url);        try {             StringEntity stringEntity = new StringEntity(new GsonBuilder().create().toJson(object));            httpPut.setEntity(stringEntity);            httpPut.setHeader("Accept", "application/json");            httpPut.setHeader("Content-type", "application/json");            httpPut.setHeader("Accept-Encoding", "gzip");             defaultHttpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, timeOut);            HttpResponse httpResponse = defaultHttpClient.execute(httpPut);            if(httpResponse.getStatusLine().getStatusCode()!=HttpStatus.SC_OK){            return null;            }            HttpEntity httpEntity = httpResponse.getEntity();            if (httpEntity != null) {                InputStream inputStream = httpEntity.getContent();                Header contentEncoding = httpResponse.getFirstHeader("Content-Encoding");                if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {                    inputStream = new GZIPInputStream(inputStream);                }                 String resultString = convertStreamToString(inputStream);                inputStream.close();                return new GsonBuilder().create().fromJson(resultString, objectClass);             }         } catch (UnsupportedEncodingException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (ClientProtocolException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (IOException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        }catch (Exception e) {e.printStackTrace();}        return null;    }//ADD    public <T> T PostObject(final String url, final T object, final Class<T> objectClass) {        DefaultHttpClient defaultHttpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost(url);        try {             StringEntity stringEntity = new StringEntity(new GsonBuilder().create().toJson(object));            httpPost.setEntity(stringEntity);            httpPost.setHeader("Accept", "application/json");            httpPost.setHeader("Content-type", "application/json");            httpPost.setHeader("Accept-Encoding", "gzip");             defaultHttpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, timeOut);            HttpResponse httpResponse = defaultHttpClient.execute(httpPost);            if(httpResponse.getStatusLine().getStatusCode()!=HttpStatus.SC_OK){            return null;            }            HttpEntity httpEntity = httpResponse.getEntity();            if (httpEntity != null) {                InputStream inputStream = httpEntity.getContent();                Header contentEncoding = httpResponse.getFirstHeader("Content-Encoding");                if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {                    inputStream = new GZIPInputStream(inputStream);                }                 String resultString = convertStreamToString(inputStream);                inputStream.close();                return new GsonBuilder().create().fromJson(resultString, objectClass);            }         } catch (UnsupportedEncodingException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (ClientProtocolException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (IOException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        }catch (Exception e) {e.printStackTrace();}        return null;    }     public <T> T PostParams(String url, final List<NameValuePair> params, final Class<T> objectClass) {        String paramString = URLEncodedUtils.format(params, "utf-8");        url += "?" + paramString;        return PostObject(url, null, objectClass);    }     private String convertStreamToString(InputStream inputStream) {        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));        StringBuilder stringBuilder = new StringBuilder();        String line = null;        try {            while ((line = bufferedReader.readLine()) != null) {                stringBuilder.append(line + "\n");            }        } catch (IOException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } finally {            try {                inputStream.close();            } catch (IOException e) {                e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.            }        }        return stringBuilder.toString();    }    //GET    public <T> T Get(String url, List<NameValuePair> params, final Class<T> objectClass) {        DefaultHttpClient defaultHttpClient = new DefaultHttpClient();        String paramString = URLEncodedUtils.format(params, "utf-8");        url += "?" + paramString;        HttpGet httpGet = new HttpGet(url);        try {            httpGet.setHeader("Accept", "application/json");            httpGet.setHeader("Accept-Encoding", "gzip");             defaultHttpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, timeOut);            HttpResponse httpResponse = defaultHttpClient.execute(httpGet);            if(httpResponse.getStatusLine().getStatusCode()!=HttpStatus.SC_OK){            return null;            }            HttpEntity httpEntity = httpResponse.getEntity();            if (httpEntity != null) {                InputStream inputStream = httpEntity.getContent();                Header contentEncoding = httpResponse.getFirstHeader("Content-Encoding");                if (contentEncoding != null && contentEncoding.getValue().equalsIgnoreCase("gzip")) {                    inputStream = new GZIPInputStream(inputStream);                }                 String resultString = convertStreamToString(inputStream);                inputStream.close();                return new GsonBuilder().create().fromJson(resultString, objectClass);            }        } catch (UnsupportedEncodingException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (ClientProtocolException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        } catch (IOException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        }catch (Exception e) {e.printStackTrace();}        return null;    }    //DELETE    public boolean Delete(String url, final List<NameValuePair> params) {        DefaultHttpClient defaultHttpClient = new DefaultHttpClient();        String paramString = URLEncodedUtils.format(params, "utf-8");        url += "?" + paramString;        HttpDelete httpDelete = new HttpDelete(url);         HttpResponse httpResponse = null;        try {        defaultHttpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, timeOut);            httpResponse = defaultHttpClient.execute(httpDelete);            if(httpResponse.getStatusLine().getStatusCode()==HttpStatus.SC_OK){            return true;            }else {return false;}        } catch (IOException e) {            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.        }catch (Exception e) {e.printStackTrace();}        return false;    }}

4）修改MainActivity代码如下

package com.example.webapitest;import java.util.ArrayList;import java.util.List;import org.apache.http.NameValuePair;import org.apache.http.message.BasicNameValuePair;import android.os.Bundle;import android.app.Activity;import android.view.Menu;public class MainActivity extends Activity {private static final String REST_SERVICE_URL = "http://10.0.9.75:88/api/";private static final String GetStudentsURL = REST_SERVICE_URL + "StudentValue/GetStudents";private static final String AddStudentURL=REST_SERVICE_URL+"StudentValue/AddStudent";private String UpdateStudentURL=REST_SERVICE_URL+"StudentValue/UpdateStudent/";private String DeleteStudentURL=REST_SERVICE_URL+"StudentValue/DeleteStudent/";private String GetStudentByIdURL=REST_SERVICE_URL+"StudentValue/GetStudentById/";//GET ONEprivate Runnable getStudentRunnable=new Runnable() {@Overridepublic void run() {GetStudentByIdURL+="1";List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();JSONHttpClient jsonHttpClient = new JSONHttpClient();            StudentInfo item = jsonHttpClient.Get(GetStudentByIdURL, nameValuePairs, StudentInfo.class);}};//Searchprivate Runnable searchStudentsRunnable=new Runnable() {            @Override            public void run() {          List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();        nameValuePairs.add(new BasicNameValuePair(StudentInfo.STUDENT_NAME, "chad"));        nameValuePairs.add(new BasicNameValuePair(StudentInfo.STUDENT_ADDRESS, ""));            JSONHttpClient jsonHttpClient = new JSONHttpClient();            StudentInfo[] items = jsonHttpClient.Get(GetStudentsURL, nameValuePairs, StudentInfo[].class);        }        };     //ADD    private Runnable addStudentsRunnable=new Runnable() {@Overridepublic void run() {StudentInfo studentInfo=new StudentInfo();studentInfo.setStuName("chad.cao");studentInfo.setStuAddress("zhejiang");JSONHttpClient jsonHttpClient = new JSONHttpClient();            StudentInfo item = jsonHttpClient.PostObject(AddStudentURL, studentInfo, StudentInfo.class);}};//UPDATEprivate Runnable updateStudentRunnable=new Runnable() {@Overridepublic void run() {UpdateStudentURL+="1";StudentInfo studentInfo=new StudentInfo();studentInfo.setStuName("chad11");studentInfo.setStuAddress("jiaxing11");JSONHttpClient jsonHttpClient=new JSONHttpClient();StudentInfo item=jsonHttpClient.PutObject(UpdateStudentURL,studentInfo , StudentInfo.class);}};//DELETEprivate Runnable deleteStudentRunnable=new Runnable() {@Overridepublic void run() {List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();JSONHttpClient jsonHttpClient = new JSONHttpClient();DeleteStudentURL+="30";            boolean flag = jsonHttpClient.Delete(DeleteStudentURL, nameValuePairs);}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);int flag=5;switch (flag) {case 1://ADDnew Thread(addStudentsRunnable).start();break;case 2://UPDATEnew Thread(updateStudentRunnable).start();break;case 3://DELETEnew Thread(deleteStudentRunnable).start();break;case 4://SEARCHnew Thread(searchStudentsRunnable).start();break;case 5://GET ONEnew Thread(getStudentRunnable).start();break;default:break;}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

5）为了能让Android调用网络数据在AndroidManifest.xml中添加代码如下

<uses-permission android:name="android.permission.INTERNET" />