问题描述

安卓，通过url获取图片动态生成ImageView为什么生成不了？可能是什么原因？

package com.example.zz670.mypic;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;
import android.widget.LinearLayout;

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

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

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

private class work extends Thread {
    InputStream inputStream = null;
    HttpURLConnection urlConnection = null;
    String response;
    String[] gURL = new String[10];
    Bitmap bitmap;
    ImageView imageView;
    LinearLayout linearLayout;
    public void run() {
        try {
            URL url = new URL("http://gank.io/api/random/data/福利/1");
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setConnectTimeout(5000);
            urlConnection.setRequestMethod("GET");
            int statusCode = urlConnection.getResponseCode();
            if (statusCode == 200) {
                inputStream = new BufferedInputStream(urlConnection.getInputStream());
                response = inputStream2String(inputStream);

            }
            if (!response.isEmpty()) {
                try {
                    JSONObject jsonObject1 = new JSONObject(response);
                    // Log.e("Json", response);
                    JSONArray jsonArray = jsonObject1.getJSONArray("results");
                    for (int i = 0; i < jsonArray.length(); i++) {
                        JSONObject jsonObject = (JSONObject) jsonArray.get(i);
                        //取出name
                        String jarray1 = jsonObject.getString("url");

                        for (int j = 0; j < 10; j++) {
                            gURL[j] = jarray1;
                            Log.e("Json", jarray1.toString());
                            // Log.e("Json", gURL[j]);
                        }
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        linearLayout = (LinearLayout) findViewById(R.id.id_gallery);
        ImageView[] imageViews = new ImageView[10];
        for (int i = 0; i < imageViews.length; i++) {

            imageViews[i] = imageView = new ImageView(MainActivity.this);
            try {
                Bitmap bitmap = getBitmap(gURL[i]);
                imageView.setImageBitmap(bitmap);
                linearLayout.addView(imageView);
            } catch (Exception e) {
            }
        }
    }

    String inputStream2String(InputStream is) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(is));
        StringBuffer buffer = new StringBuffer();
        String line = "";
        while ((line = in.readLine()) != null) {
            buffer.append(line);
        }
        return buffer.toString();
    }

    private Bitmap getBitmap(String path) throws IOException {

        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setConnectTimeout(5000);
        conn.setRequestMethod("GET");
        if (conn.getResponseCode() == 200) {
             inputStream = conn.getInputStream();
            bitmap = BitmapFactory.decodeStream(inputStream);
            return bitmap;
        }
        return null;
    }
}

}

解决方案

你是在线程里执行的 请求URL 路径，是异步的，
这里会先执行：
for (int i = 0; i < imageViews.length; i++) {

        imageViews[i] = imageView = new ImageView(MainActivity.this);
        try {
            Bitmap bitmap = getBitmap(gURL[i]);
            imageView.setImageBitmap(bitmap);
            linearLayout.addView(imageView);
        } catch (Exception e) {
        }
    }

所有 gURL[i]全是空，你可输出Log看一下。

解决方案二：

对,上面的代码必须放在handler里面执行

解决方案三：

报什么异常？有可能是AndroidManifest文件中没声明互联网使用权限造成的。