MATLAB 2012+中的Apache HttpClient

Question

我想使用apache httpclient与webservices进行交互.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中然后我可以创建到client-instance来使用:

在MATLAB 2007b和2011b中(这些是我的版本):

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)

这真是让我烦恼,因为2011b和2012b中的代码是相同的,所有jar都被加载,并且MATLAB中的两个Java版本也是相同的(1.6.0_17-b04).所以我真的不明白为什么课程在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

我也尝试将所有jar文件放到静态类路径上 - 这也没有任何影响.很高兴有关如何解决这个或如何找到问题的实际原因的任何想法...

Answer 1

您的类路径上的 httpclient 和 httpcore 版本不匹配。看来您只升级了 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/dependency.html

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