MATLAB 2012中的Apache HttpClient

Question

我想使用apache httpclient与webservices进行交互。特别是我使用的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，然后我可以创建到客户端实例来使用：

在MATLAB2007b和2011b（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

在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)

这真的让我头疼，因为2011b和2012b中的代码是相同的，所有jar都被加载了，而且MATLAB附带的两个Java版本也是相同的（1.6.0\u 17-b04）。所以我真的不明白为什么2012b的课程变得不可下载。

我尝试使用matlab classloader，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上——这也没有任何效果。很高兴有任何关于如何解决这个问题或如何找到问题的实际原因的想法......

Answer 1

类路径上的httpclient和httpcore版本不匹配。您似乎只升级了httpclient，但没有升级其依赖项。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

您还应该确保在类路径上没有多个版本的依赖项。Matlab2012b似乎已经有了httpcore的版本，这就是为什么您会遇到这种冲突。