我创建了一个涉及 JSON 解析的 android 应用程序。当我在模拟器中运行该应用程序时，它可以工作，但是当我在我的 android 手机中运行它时，它会输出错误“不幸的是已停止”。
这是我的 JSON 类：
package com.example.uichandbook;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Paint;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
Button b1;
Button copy;
Button search;
int final_id = 0;
int final_id2 = 0;
int large1 = 0;
int large2 = 0;
int counter2;
int counter1;
String parse;
// url to make request
private static String url = "http://lynda.byethost32.com/UICHandbook/contents.json";
private static String url2 = "http://lynda.byethost32.com/UICHandbook/sub_contents.json";
int id;
DatabaseHandler db = new DatabaseHandler(this);
// contacts JSONArray
JSONArray contacts = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (DetectConnection
.checkInternetConnection(MainActivity.this) == true) {
Toast.makeText(MainActivity.this,
"You have Internet Connection", Toast.LENGTH_LONG)
.show();
updates();
}
DatabaseHandler db = new DatabaseHandler(this);
List<data2> contacts = db.getAllContent();
for (data2 cn : contacts) {
LinearLayout lnr = (LinearLayout) findViewById(R.id.container);
lnr.setPadding(1, 1, 1, 1);
b1 = new Button(this);
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT); // Verbose!
lp.weight = 1.0f; // This is critical. Doesn't work without it.
b1.setId(cn.getid());
final int _id = b1.getId();
b1.setText(cn.getcontentname());
lnr.addView(b1, lp);
copy = ((Button)findViewById(_id));
copy.setOnClickListener(new View.OnClickListener(){
public void onClick(View view){
Intent intent = new Intent(MainActivity.this, subcontent.class);
intent.putExtra("id", _id);
startActivity(intent);
}
});
}
db.close();
}
public void getjson()
{
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);
try{
// Create a new HTTP Client
DefaultHttpClient defaultClient = new DefaultHttpClient();
// Setup the get request
HttpGet httpGetRequest = new HttpGet(url);
// Execute the request in the client
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
// Grab the response
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
String jsonreader = reader.readLine();
// Instantiate a JSON object from the request response
JSONObject jsonObject = new JSONObject(jsonreader);
contacts = jsonObject.getJSONArray("tbl_content");
for(int i = 0; i < contacts.length(); i++){
JSONObject c = contacts.getJSONObject(i);
Log.d("contact", c.getString("content_name"));
Log.d("contact", c.getString("content"));
Log.d("contact", c.getString("content_id"));
Log.d("contact", c.getString("book_id"));
DatabaseHandler db = new DatabaseHandler(this);
db.addcontent(new data2(c.getInt("content_id"), c.getString("content_name"),c.getString("content"),c.getInt("book_id")));
}
} catch(Exception e){
// In your production code handle any errors and catch the individual exceptions
e.printStackTrace();
}
}
public void getjson2()
{
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url2);
try{
// Create a new HTTP Client
DefaultHttpClient defaultClient = new DefaultHttpClient();
// Setup the get request
HttpGet httpGetRequest = new HttpGet(url2);
// Execute the request in the client
HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
// Grab the response
BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
String jsonreader = reader.readLine();
// Instantiate a JSON object from the request response
JSONObject jsonObject = new JSONObject(jsonreader);
contacts = jsonObject.getJSONArray("subcontent");
for(int i = 0; i < contacts.length(); i++){
JSONObject c = contacts.getJSONObject(i);
Log.d("contact", c.getString("subcontent_name"));
Log.d("contact", c.getString("subcontent"));
Log.d("contact", c.getString("subcontent_id"));
Log.d("contact", c.getString("content_id"));
DatabaseHandler db = new DatabaseHandler(this);
db.subaddcontent(new data3(c.getInt("subcontent_id"), c.getString("subcontent_name"),c.getString("subcontent"),c.getInt("content_id")));
}
} catch(Exception e){
// In your production code handle any errors and catch the individual exceptions
e.printStackTrace();
}
}
final static String SYSTEM_NEWLINE = "\n";
final static float COMPLEXITY = 5.12f; //Reducing this will increase effici ency but will decrease effectiveness
final static Paint p = new Paint();
public static void justifyText(final TextView tv, final float origWidth){
String s = tv.getText().toString();
p.setTypeface(tv.getTypeface());
String [] splits = s.split(SYSTEM_NEWLINE);
float width = origWidth - 5;
for(int x = 0; x<splits.length;x++)
if(p.measureText(splits[x])>width){
splits[x] = wrap(splits[x], width, p);
String [] microSplits = splits[x].split(SYSTEM_NEWLINE);
for(int y = 0; y<microSplits.length-1;y++)
microSplits[y] = justify(removeLast(microSplits[y], " "), width, p);
StringBuilder smb_internal = new StringBuilder();
for(int z = 0; z<microSplits.length;z++)
smb_internal.append(microSplits[z]+((z+1<microSplits.length) ? SYSTEM_NEWLINE : ""));
splits[x] = smb_internal.toString();
}
final StringBuilder smb = new StringBuilder();
for(String cleaned : splits)
smb.append(cleaned+SYSTEM_NEWLINE);
tv.setGravity(Gravity.LEFT);
tv.setText(smb);
}
private static String wrap(String s, float width, Paint p){
String [] str = s.split("\\s"); //regex
StringBuilder smb = new StringBuilder(); //save memory
smb.append(SYSTEM_NEWLINE);
for(int x = 0; x<str.length; x++){
float length = p.measureText(str[x]);
String [] pieces = smb.toString().split(SYSTEM_NEWLINE);
try{
if(p.measureText(pieces[pieces.length-1])+length>width)
smb.append(SYSTEM_NEWLINE);
}catch(Exception e){}
smb.append(str[x] + " ");
}
return smb.toString().replaceFirst(SYSTEM_NEWLINE, "");
}
private static String removeLast(String s, String g){
if(s.contains(g)){
int index = s.lastIndexOf(g);
int indexEnd = index + g.length();
if(index == 0) return s.substring(1);
else if(index == s.length()-1) return s.substring(0, index);
else
return s.substring(0, index) + s.substring(indexEnd);
}
return s;
}
private static String justifyOperation(String s, float width, Paint p){
float holder = (float) (COMPLEXITY*Math.random());
while(s.contains(Float.toString(holder)))
holder = (float) (COMPLEXITY*Math.random());
String holder_string = Float.toString(holder);
float lessThan = width;
int timeOut = 100;
int current = 0;
while(p.measureText(s)<lessThan&¤t<timeOut) {
s = s.replaceFirst(" ([^"+holder_string+"])", " "+holder_string+"$1");
lessThan = p.measureText(holder_string)+lessThan-p.measureText(" ");
current++;
}
String cleaned = s.replaceAll(holder_string, " ");
return cleaned;
}
private static String justify(String s, float width, Paint p){
while(p.measureText(s)<width){
s = justifyOperation(s,width, p);
}
return s;
}
public void updates()
{
DatabaseHandler db = new DatabaseHandler(this);
db.deletetable1();
db.deletetable2();
getjson();
//getjson2();
}
}