【安卓学习之常见问题】 编译android8.0问题- 'The import org.apache.http.HttpEntity cannot be resolved'.

█ 【安卓学习之常见问题】 编译android8.0问题- ‘The import org.apache.http.HttpEntity cannot be resolved’.

█ 问题：

　●　由于某些原因要使用android8.0的特性，因此将原来的编译环境从android4.4.2(target=android-19)升级到android5.0.1(target=android-21)，编译没有出问题，再次升级到android8.0.0(target=android-26)，就出现编译问题
　●　编译下，在appcompat\res\values-v23\styles_base.xml出现如下问题：

★The project was not built since its build path is incomplete. Cannot find the class file for
★org.apache.http.NameValuePair. Fix the build path then try building this project
★The method sqrt(float) is undefined for the type FloatMath
★The type org.apache.http.NameValuePair cannot be resolved. It is indirectly referenced from required .class
★The method ceil(float) is undefined for the type FloatMath
★BasicNameValuePair cannot be resolved to a type
★HttpPost cannot be resolved to a type
★NameValuePair cannot be resolved to a type
★HttpClient cannot be resolved to a type
★HTTP cannot be resolved to a variable
★HttpEntity cannot be resolved to a type
★EntityUtils cannot be resolved
★HttpResponse cannot be resolved to a type
★DefaultHttpClient cannot be resolved to a type
……

█ 解决：

　●　1.这些问题都比较好解决，网上都有很多教程，一个一个百度，如The import org.apache.http.HttpEntity cannot be resolved，就是找不到对应的类。The method sqrt(float) is undefined for the type FloatMath，就是找不到对应的方法。

　●　2.FloatMath.sqrt和FloatMath.ceil方法过时：直接替换为(float) Math.ceil和(float) Math.sqrt
　 　 PS:Math.ceil和Math.sqrt的返回值是double类型，有必要的情况下，需要进行类型转换！　

　●　2.HttpClient库：进入apache官网，下载【4.5.5.zip 】

Release 4.5.5

HttpClient 4.5.5 (GA) is a maintenance release that fixes a regression introduced
by the previous release causing a NPE in SystemDefaultCredentialsProvider.
Please note that as of 4.4 HttpClient requires Java 1.6 or newer.
Last Published: 2018-01-22

　 　下载之后如下：
　 　
　 　 PS:这边我们主要用到httpclient-4.5.5.jar和httpcore-4.4.9.jar两个库
　

█ 总结：

　●　由于android sdk将部分库删掉，所以只能使用新的sdk，就需要添加删掉的那些库

　
下载地址：httpcomponents-client-4.5.5-bin和src_20180518.zip-CSDN下载(org.apache.http的相关类，android高版本SDK需要用到，解决’The import org.apache.http.HttpEntity cannot be resolved’>等问题)　

　●　由于引入了V7和新的sdk,将导致另一个问题的产生：

[Dex Loader] Unable to execute dex: Cannot merge new index 66457 into a non-jumbo instruction!
[XXX] Conversion to Dalvik format failed: Unable to execute dex: Cannot merge new index 66457 into a non-jumbo instruction!
　
　

　 　 PS1:将jar合并类成dex时，每一个方法都分配有一个id(合并类)，当方法超过65535，就会遇到这个问题,解决方法就是在
　 　 PS2:解决方法就是在在project.properties文件末尾处添加【dex.force.jumbo=true】，记得要clean/清理工程，并重新编译。

█ 相关资料：

　●　1.2013-07-11【已解决】Eclipse的java代码出错：The import org.apache cannot be resolved – 在路上
　●　2.2013-07-23 异常分析：Unable to execute dex: Cannot merge new index 71813 into a non-jumbo instruction! - super_spy的专栏 -CSDN博客
　●　3.2014-06-23 Android-Cannot merge new index 66195 into a non-jumbo instruction的解决办法 - 若鱼的专栏 - CSDN博客

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http://blog.csdn.net/ljb568838953/article/details/80409666