无法在android中下载图像

我需要下载我的twitter个人资料图片，并在点击按钮的图像视图中显示它。下面是我下载所需用户的个人资料图片的代码

public static InputStream getTwitterProfilePictureOfUser(String twitterId){
    try {
        return new DefaultHttpClient().execute(new HttpGet("http://api.twitter.com/1/users/profile_image?user_id="+twitterId+"&size=bigger")).getEntity().getContent();
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    } 
} 

获取以下异常。我错在哪里

 javax.net.ssl.SSLException: Not trusted server certificate
at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:371)
at org.apache.http.conn.ssl.AbstractVerifier.verify(AbstractVerifier.java:92)
at org.apache.http.conn.ssl.SSLSocketFactory.createSocket(SSLSocketFactory.java:381)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:174)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:348)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
at com.tarams.android.giveblood.service.ServiceStub.getTwitterProfilePictureOfUser(ServiceStub.java:207)
    at com.tarams.android.giveblood.activities.ProfileActivity.onCreate(ProfileActivity.java:128)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2633)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2685)
at android.app.ActivityThread.access$2300(ActivityThread.java:126)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2038)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4633)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method)
   Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: TrustAnchor for CertPath not found.
at org.apache.harmony.xnet.provider.jsse.TrustManagerImpl.checkServerTrusted(TrustManagerImpl.java:168)
at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:366)
... 24 more
 Caused by: java.security.cert.CertPathValidatorException: TrustAnchor for CertPath not found.
at org.bouncycastle.jce.provider.PKIXCertPathValidatorSpi.engineValidate(PKIXCertPathValidatorSpi.java:149)
at java.security.cert.CertPathValidator.validate(CertPathValidator.java:202)
at org.apache.harmony.xnet.provider.jsse.TrustManagerImpl.checkServerTrusted(TrustManagerImpl.java:164)

---

您正试图通过连接到HTTPS URL，而运行代码的设备不信任站点提供的SSL证书。我建议您阅读这篇关于在ApacheHTTP客户机中设置信任的文章