mybatis-generator通过JavaParser工具实现Java代码合并

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首先附上我扩展后项目的github地址 点击打开链接

用过mybatis-generator的人应该都清楚，它默认是不支持Java代码合并的，只支持XML合并，这给我们的开发工作带来了一些麻烦。查看源代码

它默认的代码是这样的：    /* (non-Javadoc)     * @see org.mybatis.generator.api.ShellCallback#mergeJavaFile(java.lang.String, java.lang.String, java.lang.String[], java.lang.String)     */    public String mergeJavaFile(String newFileSource,            String existingFileFullPath, String[] javadocTags, String fileEncoding)            throws ShellException {        throw new UnsupportedOperationException();    }
仅仅是抛出了一个不支持的异常。如是我试着去扩展了这个接口，中间借助了JavaParser这个用于解析Java文件的工具,附上它的github地址：点击打开链接
在引用它的maven包的时候我发现，原来mybatis-generator中也对它有使用，只是版本比较低，我将其改成了高版本的，修改后如下：<!-- TODO: Raising above 2.4.0 required jdk 8 usage -->            <dependency>                <groupId>com.github.javaparser</groupId>                <artifactId>javaparser-core</artifactId>                <version>3.2.10</version>                <!--<scope>test</scope>-->            </dependency>
最后我重写了mergeJavaFile方法，这个代码如下：

public String mergeJavaFile(String newFileSource,                                String existingFileFullPath)            throws ShellException, FileNotFoundException {        return new JavaFileMergerJaxp().getNewJavaFile(newFileSource,existingFileFullPath);    }

 public String getNewJavaFile(String newFileSource, String existingFileFullPath) throws FileNotFoundException {        CompilationUnit newCompilationUnit = JavaParser.parse(newFileSource);        CompilationUnit existingCompilationUnit = JavaParser.parse(new File(existingFileFullPath));        return mergerFile(newCompilationUnit,existingCompilationUnit);    }

public String mergerFile(CompilationUnit newCompilationUnit,CompilationUnit existingCompilationUnit){        StringBuilder sb = new StringBuilder(newCompilationUnit.getPackageDeclaration().get().toString());        newCompilationUnit.removePackageDeclaration();        //合并imports        NodeList<ImportDeclaration> imports = newCompilationUnit.getImports();        imports.addAll(existingCompilationUnit.getImports());        Set importSet = new HashSet<ImportDeclaration>();        importSet.addAll(imports);        NodeList<ImportDeclaration> newImports = new NodeList<>();        newImports.addAll(importSet);        newCompilationUnit.setImports(newImports);        for (ImportDeclaration i:newCompilationUnit.getImports()) {            sb.append(i.toString());        }        newLine(sb);        NodeList<TypeDeclaration<?>> types = newCompilationUnit.getTypes();        NodeList<TypeDeclaration<?>> oldTypes = existingCompilationUnit.getTypes();        for (int i = 0;i<types.size();i++) {            //截取Class            String classNameInfo = types.get(i).toString().substring(0, types.get(i).toString().indexOf("{")+1);            sb.append(classNameInfo);            newLine(sb);            newLine(sb);            //合并fields            List<FieldDeclaration> fields = types.get(i).getFields();            List<FieldDeclaration> oldFields = oldTypes.get(i).getFields();            List<FieldDeclaration> newFields = new ArrayList<>();            HashSet<FieldDeclaration> fieldDeclarations = new HashSet<>();            fieldDeclarations.addAll(fields);            fieldDeclarations.addAll(oldFields);            newFields.addAll(fieldDeclarations);            for (FieldDeclaration f: newFields){                sb.append(f.toString());                newLine(sb);                newLine(sb);            }            //合并methods            List<MethodDeclaration> methods = types.get(i).getMethods();            List<MethodDeclaration> existingMethods = oldTypes.get(i).getMethods();            for (MethodDeclaration f: methods){                sb.append(f.toString());                newLine(sb);                newLine(sb);            }            for (MethodDeclaration m:existingMethods){                boolean flag = true;                for (String tag : MergeConstants.OLD_ELEMENT_TAGS) {                    if (m.toString().contains(tag)) {                        flag = false;                        break;                    }                }                if (flag){                    sb.append(m.toString());                    newLine(sb);                    newLine(sb);                }            }            //判断是否有内部类            types.get(i).getChildNodes();            for (Node n:types.get(i).getChildNodes()){                if (n.toString().contains("static class")){                    sb.append(n.toString());                }            }        }        return sb.append(System.getProperty("line.separator")+"}").toString();    }

希望能给大家带来一些参考

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