spring boot 之使用mapstruct

　　最近在阅读swagger源码，当看到 springfox.documentation.swagger2.mappers.modelmapper 类时，无意中看到该类上面使用的 org.mapstruct.mapper 注解时，对这个注解一时竟想不出个所意然来。便打开百度搜索了一番，有关这个注解的文章不是很多，从这些文章中了解到，这个注解跟jsr 269 有关，下面列出这个注解相关的文章链接。

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 相关的文章链接：

1.  mapstruct官网 http://mapstruct.org/
2.  mapstruct github网址：https://github.com/mapstruct/mapstruct
3. jsr 269: pluggable annotation processing api  https://jcp.org/en/jsr/detail?id=269
4. 插入式注解处理api(pluggable annotation processing api)  https://blog.csdn.net/yczz/article/details/34116189
5. mapstruct实体间转换快速入门  https://blog.csdn.net/lx_yoyo/article/details/75061614

　　当看完上面的几篇的文章之后，对这个注解到底起何作用，仍然是一知半解。于是参照上面列表中的 mapstruct实体间转换快速入门 ，当我把工程建好，copy完相关的代码之后，根据文章的提示，执行mvn install（mvn compile）命令之后，没有出现文章中提到的在 target\generated-sources\annotations 会自动生成peoplemapperimpl.java 源文件，反到是控制台打印出的日志信息提示编译失败，错误信息如下所示：

 

[info] -------------------------------------------------------------
[error] compilation error : 
[info] -------------------------------------------------------------
[error] /f:/java.ws.01/springboot-example/example4/src/main/java/com/github/torlight/sbex/peoplemapper.java:[21,15] no property named "age" exists in source parameter(s). did you mean "null"?
[error] /f:/java.ws.01/springboot-example/example4/src/main/java/com/github/torlight/sbex/peoplemapper.java:[32,10] no property named "user.name" exists in source parameter(s). did you mean "null"?
[info] 2 errors 
[info] -------------------------------------------------------------
[info] ------------------------------------------------------------------------
[info] build failure
[info] ------------------------------------------------------------------------
[info] total time: 5.951 s
[info] finished at: 2018-08-19t10:52:59+08:00
[info] final memory: 26m/282m
[info] ------------------------------------------------------------------------
[error] failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.5.1:compile (default-compile) on project example4: compilation failure: compilation failure:
[error] /f:/java.ws.01/springboot-example/example4/src/main/java/com/github/torlight/sbex/peoplemapper.java:[21,15] no property named "age" exists in source parameter(s). did you mean "null"?
[error] /f:/java.ws.01/springboot-example/example4/src/main/java/com/github/torlight/sbex/peoplemapper.java:[32,10] no property named "user.name" exists in source parameter(s). did you mean "null"?
[error] -> [help 1]
org.apache.maven.lifecycle.lifecycleexecutionexception: failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.5.1:compile (default-compile) on project example4: compilation failure
    at org.apache.maven.lifecycle.internal.mojoexecutor.execute(mojoexecutor.java:212)
    at org.apache.maven.lifecycle.internal.mojoexecutor.execute(mojoexecutor.java:153)
    at org.apache.maven.lifecycle.internal.mojoexecutor.execute(mojoexecutor.java:145)
    at org.apache.maven.lifecycle.internal.lifecyclemodulebuilder.buildproject(lifecyclemodulebuilder.java:116)
    at org.apache.maven.lifecycle.internal.lifecyclemodulebuilder.buildproject(lifecyclemodulebuilder.java:80)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.singlethreadedbuilder.build(singlethreadedbuilder.java:51)
    at org.apache.maven.lifecycle.internal.lifecyclestarter.execute(lifecyclestarter.java:128)
    at org.apache.maven.defaultmaven.doexecute(defaultmaven.java:307)
    at org.apache.maven.defaultmaven.doexecute(defaultmaven.java:193)
    at org.apache.maven.defaultmaven.execute(defaultmaven.java:106)
    at org.apache.maven.cli.mavencli.execute(mavencli.java:862)
    at org.apache.maven.cli.mavencli.domain(mavencli.java:286)
    at org.apache.maven.cli.mavencli.main(mavencli.java:197)
    at sun.reflect.nativemethodaccessorimpl.invoke0(native method)
    at sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:62)
    at sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:43)
    at java.lang.reflect.method.invoke(method.java:498)
    at org.codehaus.plexus.classworlds.launcher.launcher.launchenhanced(launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.launcher.launch(launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.launcher.mainwithexitcode(launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.launcher.main(launcher.java:356)
caused by: org.apache.maven.plugin.compiler.compilationfailureexception: compilation failure
    at org.apache.maven.plugin.compiler.abstractcompilermojo.execute(abstractcompilermojo.java:972)
    at org.apache.maven.plugin.compiler.compilermojo.execute(compilermojo.java:129)
    at org.apache.maven.plugin.defaultbuildpluginmanager.executemojo(defaultbuildpluginmanager.java:134)
    at org.apache.maven.lifecycle.internal.mojoexecutor.execute(mojoexecutor.java:208)
    ... 20 more
[error] 
[error] 
[error] for more information about the errors and possible solutions, please read the following articles:
[error] [help 1] http://cwiki.apache.org/confluence/display/maven/mojofailureexception

 

　　当出现上面的错误之后，先是在网上找了一下，但没有找到相关的资料，没办法只能靠自己解决了。查看工程的pom.xml文件，有用到maven-compiler-plugin 插件，看到该插件的配置项中mapstruct-processor ，心里也清楚当maven执行maven-compiler-plugin 插件中相关类的方法时，肯定会执行mapstruct-processor 中相关类的方法。可是不清楚具体会先从那个类的方法开始执行。

　　没办法，只能根据上面的异常提示信息，在maven源码工程中一路跟踪下来，发现错误源是当执行sourcereference类的getsourceentries方法时触发的。no property named "age" exists in source parameter(s). did you mean "null"?  在被转换的实体中找不到age属性，可是在peopleentity 实体中本来就存在age属性。原来报错是因为getsourceentries方法是通过反射读取实体的get方法来获取属性，然后再进行属性比较，怪不得会报错。当找到报错的原因之后，我把目光停留在源码中的注释 //constructor, getters, setters etc.  原来实体中的getter，setter 方法都被省略了。

 

 1 package com.github.torlight.sbex;
 2 
 3 public class peopleentity {
 4     private integer age;
 5     private string name;
 6     private string callnumber;
 7     private string address;
 8     private string email;
 9     
10     public peopleentity() {
11         
12     }
13 
14     public peopleentity(integer age, string name, string callnumber, string address, string email) {
15         this.age = age;
16         this.name = name;
17         this.callnumber = callnumber;
18         this.address = address;
19         this.email = email;
20     }
21     
22 　　//constructor, getters, setters etc.
23 
24 }

 

 

---

 修改之后的代码：

 1 package com.github.torlight.sbex;
 2 
 3 public class peopledto {
 4     
 5     private string phonenumber;
 6     private string address;
 7     private string email;
 8     private user  user;
 9     
10     public peopledto() {
11     
12     }
13 
14     public peopledto(string phonenumber, string address, string email, user user) {
15         this.phonenumber = phonenumber;
16         this.address = address;
17         this.email = email;
18         this.user = user;
19     }
20 
21     public string getphonenumber() {
22         return phonenumber;
23     }
24 
25     public void setphonenumber(string phonenumber) {
26         this.phonenumber = phonenumber;
27     }
28 
29     public string getaddress() {
30         return address;
31     }
32 
33     public void setaddress(string address) {
34         this.address = address;
35     }
36 
37     public string getemail() {
38         return email;
39     }
40 
41     public void setemail(string email) {
42         this.email = email;
43     }
44 
45     public user getuser() {
46         return user;
47     }
48 
49     public void setuser(user user) {
50         this.user = user;
51     }
52     
53 }

 

 1 package com.github.torlight.sbex;
 2 
 3 public class peopleentity {
 4     private integer age;
 5     private string name;
 6     private string callnumber;
 7     private string address;
 8     private string email;
 9     
10     public peopleentity() {
11         
12     }
13 
14     public peopleentity(integer age, string name, string callnumber, string address, string email) {
15         this.age = age;
16         this.name = name;
17         this.callnumber = callnumber;
18         this.address = address;
19         this.email = email;
20     }
21 
22     public integer getage() {
23         return age;
24     }
25 
26     public void setage(integer age) {
27         this.age = age;
28     }
29 
30     public string getname() {
31         return name;
32     }
33 
34     public void setname(string name) {
35         this.name = name;
36     }
37 
38     public string getcallnumber() {
39         return callnumber;
40     }
41 
42     public void setcallnumber(string callnumber) {
43         this.callnumber = callnumber;
44     }
45 
46     public string getaddress() {
47         return address;
48     }
49 
50     public void setaddress(string address) {
51         this.address = address;
52     }
53 
54     public string getemail() {
55         return email;
56     }
57 
58     public void setemail(string email) {
59         this.email = email;
60     }
61 
62 }   

 

package com.github.torlight.sbex;

public class user {
    private integer age;
    private string name;
    
    public user() {

    }

    public user(integer age, string name) {
        this.age = age;
        this.name = name;
    }

    public integer getage() {
        return age;
    }

    public void setage(integer age) {
        this.age = age;
    }

    public string getname() {
        return name;
    }

    public void setname(string name) {
        this.name = name;
    }
}

　　

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　　执行mvn install（mvn compile）命令之后，控制台没有提示报错，但在 \target\generated-sources\annotations\ 文件夹下面还是空的，奇怪了？ 先执行mvn clean 然后再执行 mvn install（mvn compile）之后，终于出现了peoplemapperimpl.java 源文件。要确保 target\class 文件夹下面为空时，执行mvn install（mvn compile）命令才能生成java源文件。

 

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示例代码： https://github.com/gittorlight/springboot-example/tree/master/example4