引入WxPayException，替代原有的异常处理类，并做相应的优化

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/exception/WxPayException.java

@@ -0,0 +1,153 @@
+package com.github.binarywang.wxpay.exception;
+
+import com.github.binarywang.wxpay.bean.result.WxPayBaseResult;
+import com.google.common.base.Joiner;
+
+/**
+ * <pre>
+ * 微信支付异常结果类
+ * Created by Binary Wang on 2017-6-6.
+ * </pre>
+ */
+public class WxPayException extends Exception {
+  private String customErrorMsg;
+  /**
+   * 返回状态码
+   */
+  private String returnCode;
+  /**
+   * 返回信息
+   */
+  private String returnMsg;
+
+  /**
+   * 业务结果
+   */
+  private String resultCode;
+
+  /**
+   * 错误代码
+   */
+  private String errCode;
+
+  /**
+   * 错误代码描述
+   */
+  private String errCodeDes;
+
+  /**
+   * 微信支付返回的结果xml字符串
+   */
+  private String xmlString;
+
+  public WxPayException(String customErrorMsg) {
+    super(customErrorMsg);
+    this.customErrorMsg = customErrorMsg;
+  }
+
+  private WxPayException(Builder builder) {
+    super(builder.buildErrorMsg());
+    returnCode = builder.returnCode;
+    returnMsg = builder.returnMsg;
+    resultCode = builder.resultCode;
+    errCode = builder.errCode;
+    errCodeDes = builder.errCodeDes;
+    xmlString = builder.xmlString;
+  }
+
+  public static WxPayException from(WxPayBaseResult payBaseResult) {
+    return WxPayException.newBuilder()
+      .xmlString(payBaseResult.getXmlString())
+      .returnMsg(payBaseResult.getReturnMsg())
+      .returnCode(payBaseResult.getReturnCode())
+      .resultCode(payBaseResult.getResultCode())
+      .errCode(payBaseResult.getErrCode())
+      .errCodeDes(payBaseResult.getErrCodeDes())
+      .build();
+  }
+
+  public String getXmlString() {
+    return this.xmlString;
+  }
+
+  public String getReturnCode() {
+    return this.returnCode;
+  }
+
+  public String getReturnMsg() {
+    return this.returnMsg;
+  }
+
+  public String getResultCode() {
+    return this.resultCode;
+  }
+
+  public String getErrCode() {
+    return this.errCode;
+  }
+
+  public String getErrCodeDes() {
+    return this.errCodeDes;
+  }
+
+  public static Builder newBuilder() {
+    return new Builder();
+  }
+
+  public static final class Builder {
+    private String returnCode;
+    private String returnMsg;
+    private String resultCode;
+    private String errCode;
+    private String errCodeDes;
+    private String xmlString;
+
+    private Builder() {
+    }
+
+    public Builder returnCode(String returnCode) {
+      this.returnCode = returnCode;
+      return this;
+    }
+
+    public Builder returnMsg(String returnMsg) {
+      this.returnMsg = returnMsg;
+      return this;
+    }
+
+    public Builder resultCode(String resultCode) {
+      this.resultCode = resultCode;
+      return this;
+    }
+
+    public Builder errCode(String errCode) {
+      this.errCode = errCode;
+      return this;
+    }
+
+    public Builder errCodeDes(String errCodeDes) {
+      this.errCodeDes = errCodeDes;
+      return this;
+    }
+
+    public Builder xmlString(String xmlString) {
+      this.xmlString = xmlString;
+      return this;
+    }
+
+    public WxPayException build() {
+      return new WxPayException(this);
+    }
+
+    public String buildErrorMsg() {
+      return Joiner.on("，").skipNulls().join(new String[]{
+        returnCode == null ? null : String.format("返回代码：[%s]", returnCode),
+        returnMsg == null ? null : String.format("返回信息：[%s]", returnMsg),
+        resultCode == null ? null : String.format("结果代码：[%s]", resultCode),
+        errCode == null ? null : String.format("错误代码：[%s]", errCode),
+        errCodeDes == null ? null : String.format("错误详情：[%s]", errCodeDes),
+        xmlString == null ? null : "微信返回的原始报文：\n" + xmlString,
+      });
+    }
+  }
+}