我想使用 apache httpclient 与 web 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
因此，在 MATLAB 中，我将所有包含的 jar 加载到 javaclasspath 中，然后我可以创建客户端实例以使用：
在 MATLAB 2007b 和 2011b 中（这些是我拥有的版本）：
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 附带的两个 Java 版本也是相同的（1.6.0_17-b04）。所以我真的不明白为什么类在 2012b 中变得无法加载。
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 文件放到静态类路径中——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实际原因的任何想法......