java - MATLAB 2012+ 中的 Apache HttpClient

Question

我想使用 apache httpclient 与网络服务交互。具体来说我正在使用 http://mirror.arcor-online.net/www.apache.org//httpcomponents/httpclient/binary/httpcomponents-client-4.3-bin.zip

所以在 MATLAB 中，我将所有包含的 jar 加载到 javaclasspath 中，然后我可以创建要使用的客户端实例:

在 MATLAB 2007b 和 2011b 中(我有这些版本):

client = org.apache.http.impl.client.HttpClients.createDefault()
client =

org.apache.http.impl.client.InternalHttpClient@1e89831

2012b:

>> client = org.apache.http.impl.client.HttpClients.createDefault()

Java exception occurred:
java.lang.NoSuchFieldError: INSTANCE

    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:52)

    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:56)

    at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<clinit>(DefaultHttpRequestWriterFactory.java:46)

    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<init>(ManagedHttpClientConnectionFactory.java:72)

    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<init>(ManagedHttpClientConnectionFactory.java:84)

    at org.apache.http.impl.conn.ManagedHttpClientConnectionFactory.<clinit>(ManagedHttpClientConnectionFactory.java:59)

    at
    org.apache.http.impl.conn.PoolingHttpClientConnectionManager$InternalConnectionFactory.<init>(PoolingHttpClientConnectionManager.java:487)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:147)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:136)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:112)

    at org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:710)

    at org.apache.http.impl.client.HttpClients.createDefault(HttpClients.java:58)


>> client = org.apache.http.impl.client.HttpClients.createDefault()
Java exception occurred:
java.lang.NoClassDefFoundError: Could not initialize class org.apache.http.impl.conn.ManagedHttpClientConnectionFactory

    at
    org.apache.http.impl.conn.PoolingHttpClientConnectionManager$InternalConnectionFactory.<init>(PoolingHttpClientConnectionManager.java:487)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:147)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:136)

    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.<init>(PoolingHttpClientConnectionManager.java:112)

    at org.apache.http.impl.client.HttpClientBuilder.build(HttpClientBuilder.java:710)

    at org.apache.http.impl.client.HttpClients.createDefault(HttpClients.java:58)

这真的让我很烦，因为 2011b 和 2012b 中的代码是相同的，所有 jar 都已加载，并且 MATLAB 随附的两个 Java 版本也相同 (1.6.0_17-b04)。所以我真的不明白为什么类在 2012b 中变得不可加载。

我尝试使用 matlab 类加载器 - 但这让我更加困惑:

>> jloader =  com.mathworks.jmi.ClassLoaderManager.getClassLoaderManager();
>> jloader.loadClass('org.apache.http.impl.conn.ManagedHttpClientConnectionFactory')
Java exception occurred:
java.lang.NoClassDefFoundError: Could not initialize class org.apache.http.impl.conn.ManagedHttpClientConnectionFactory

    at java.lang.Class.forName0(Native Method)

    at java.lang.Class.forName(Unknown Source)

    at com.mathworks.jmi.ClassLoaderManager.loadClass(ClassLoaderManager.java:440)


>> jloader.getCurrentClassLoader.loadClass('org.apache.http.impl.conn.ManagedHttpClientConnectionFactory')

ans =

class org.apache.http.impl.conn.ManagedHttpClientConnectionFactory

我还尝试将所有 jar 文件放入静态类路径 - 这也没有任何效果。很高兴关于如何解决这个问题或如何找到问题的真正原因的任何想法...

Answer 1

您的类路径中的 httpclient 和 httpcore 版本不匹配。看来您只升级了 httpclient 但没有升级它的依赖项。您可以在 Apache HttpClient 项目页面上看到依赖项列表。 http://hc.apache.org/httpcomponents-client-4.3.x/httpclient/dependencies.html

您还应该确保类路径上没有多个版本的依赖项。似乎 MATLAB 2012b 已经有一个 httpcore 版本，这就是您遇到此冲突的原因。