我想将检索到的数据从服务器发送到我的Android客户端......我使用了json对象来做到这一点。这是我的servlet代码。
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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;
public class AvailabilityResponse extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("application/json");
PrintWriter out=response.getWriter();
String br_id;
br_id=request.getParameter("branchname");
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:8888/atmlivedetails","root","root");
Statement st=con.createStatement();
ResultSet rs=st.executeQuery("select atmbrno, atmbrname from location_stat where act_brname='"+br_id+"'");
while(rs.next()){
String s = rs.getString("atmbrno");
String t = rs.getString("atmbrname");
JSONObject arrayObj = new JSONObject();
arrayObj.put("atmbrno",s);
arrayObj.put("atmbrname",t);
out.print(arrayObj);
}
rs.close ();
st.close ();
}
catch(Exception e){
out.print(e);
}
}
}
这是我的机器人代码..
import java.util.ArrayList;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.ParseException;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.ClientProtocolException;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import android.os.Bundle;
public class CheckAvailability extends Activity{
Button but1,but2;
EditText brName;
TextView txt1;
String text;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.availability);
brName =(EditText)findViewById(R.id.editText1);
but1 = (Button)findViewById(R.id.button5);
but2 = (Button)findViewById(R.id.button6);
txt1 = (TextView)findViewById(R.id.textView3);
but1.setOnClickListener(new View.OnClickListener(){
public void onClick(View v){
String result = null;
InputStream is = null;
StringBuilder sb=null;
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("branchname", brName.getText().toString()));
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://10.0.2.2:8080/hello/AvailabilityResponse");
httppost.setEntity(new UrlEncodedFormEntity(postParameters));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line="0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
//paring data
String atm_id;
String atm_name;
try{
JSONArray jArray = new JSONArray(result);
JSONObject json_data=null;
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
atm_id=json_data.getString("atmbrno");
atm_name=json_data.getString("atmbrname");
//txt1.setText(atm_name);
}
}catch(JSONException e1){
Toast.makeText(getBaseContext(), "No DATA Found", Toast.LENGTH_LONG).show();
}catch (ParseException e1){
e1.printStackTrace();
}
}
});
} }
但是当我运行它总是给我“没有找到数据”例外...任何人都可以帮助我吗？
答案 0 :(得分：4)
您的servlet只返回N个JSON对象。但是你给JSON数组的响应可能是错误在你的servlet中尝试这个代码
try{
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:8888/atmlivedetails","root","root");
Statement st=con.createStatement();
ResultSet rs=st.executeQuery("select atmbrno, atmbrname from location_stat where act_brname='"+br_id+"'");
int i=0;
JSONArray jArray = new JSONArray();
while(rs.next()){
String s = rs.getString("atmbrno");
String t = rs.getString("atmbrname");
JSONObject arrayObj = new JSONObject();
arrayObj.put("atmbrno",s);
arrayObj.put("atmbrname",t);
jArray.add(i,arrayObj);
i++;
}
rs.close ();
st.close ();
out.print(jArray);
}
答案 1 :(得分：0)
在处理json字符串（转换为json对象）之前从服务器打印响应，以便您可以跟踪实际原因。你实际上得到了json异常。
答案 2 :(得分：0)
写入outputstream后，您需要关闭Printwriter这样的对象。
out.close()
答案 3 :(得分：0)
您需要将json-lib-2.4-jdk15.jar文件添加到项目类路径中，并使用以下代码创建JSON对象。
JSONObject jsonData = new JSONObject();
jsonData.put("key1", "value1");
jsonData.put("key2", "value2");
jsonData.put("key3", "value3");
System.out.println("JSON data: "+jsonData.toString());
控制台您将获得输出：JSON数据：{“key1”：“value1”，“key2”：“value2”，“key3”：“value3”}