通过读取表结构，生成对应的实体文件

忘是亡心i 2021-07-25 22:03 297阅读 0赞

在开发过程中，需要将java实体跟数据库表中的字段进行对应，几乎都是重复的机械的工作。虽然可以使用JPA工程的映射，但是还是不够人性化，需要后期进行大量的修改和对应。

本着“懒惰,首先是人类进步”的原则。开发一个工具类，进行自动的读取并影射字段。

可以通过配置，全库进行映射，也可以指定表进行映射。

不足之处，还没有好的办法将表字段的备注写入到对应的字段上。如果有人有好的解决办法，可以留言给我，我进行完善。

import java.io.File;  
    import java.io.FileWriter;  
    import java.io.IOException;  
    import java.io.PrintWriter;  
    import java.sql.Connection;  
    import java.sql.DatabaseMetaData;  
    import java.sql.DriverManager;  
    import java.sql.ResultSet;  
    import java.sql.ResultSetMetaData;  
    import java.sql.SQLException;  
    import java.sql.Statement;  
    import java.util.ArrayList;
    import java.util.Arrays;
    import java.util.Date;  
    import java.util.List;
    import java.util.regex.Matcher;
    import java.util.regex.Pattern;
    /**
     * 需要添加对应的驱动
     * @author 
     *
     */
    public class GenEntityOracle {
    	private String packageOutPath = "com.caohl";//指定实体生成所在包的路径  
        private String authorName = "";//作者名字  
        private String tablename = "";//表名  
        private String[] colnames; // 列名数组  
        private String[] colTypes; //列名类型数组  
        private int[] colSizes; //列名大小数组  
        private boolean f_util = false; // 是否需要导入包java.util.*  
        private boolean f_sql = false; // 是否需要导入包java.sql.*  
        private boolean f_jpa = true; // 是否需要生成基于注解的JPA实体对象  
        private boolean allTalbe =false;//true为全部的表，false指定表，下面的list
        private boolean f_setGet = false;//是否生成set/get方法。
        private List LIST= Arrays.asList("STANDARD_ADJUST_FAMILY");//指定需要生成的表
        private static Pattern linePattern = Pattern.compile("_(\\w)");//下划线转换为驼峰
        
          
        //数据库连接  
         private static final String URL ="jdbc:oracle:thin:@127.0.0.1:1521/ora18c";  
         private static final String NAME = "root";  
         private static final String PASS = "root";  
         private static final String DRIVER ="oracle.jdbc.driver.OracleDriver";  
           
          
        /* 
         * 构造函数 
         */  
        public GenEntityOracle(){  
            //获取表名称  
            List<String> list=getTableName();  
            for(int p=0;p<list.size();p++){  
                tablename=list.get(p);  
                //创建连接  
                Connection con=null;  
                //查要生成实体类的表  
                String sql = "select * from " + tablename;  
                Statement pStemt = null;  
                try {  
                    try {  
                        Class.forName(DRIVER);  
                    } catch (ClassNotFoundException e1) {  
                        e1.printStackTrace();  
                    }  
                    con = DriverManager.getConnection(URL,NAME,PASS);  
                    pStemt = (Statement) con.createStatement();  
                    ResultSet rs = pStemt.executeQuery(sql);  
                    ResultSetMetaData rsmd = rs.getMetaData();  
                    int size = rsmd.getColumnCount();   //统计列  
                    colnames = new String[size];  
                    colTypes = new String[size];  
                    colSizes = new int[size];  
                    for (int i = 0; i < size; i++) {  
                        colnames[i] = rsmd.getColumnName(i + 1);  
                        colTypes[i] = rsmd.getColumnTypeName(i + 1);  
                          
                        if(colTypes[i].equalsIgnoreCase("date") || colTypes[i].equalsIgnoreCase("timestamp")){  
                            f_util = true;  
                        }  
                        if(colTypes[i].equalsIgnoreCase("blob") || colTypes[i].equalsIgnoreCase("char")){  
                            f_sql = true;  
                        }  
                        colSizes[i] = rsmd.getColumnDisplaySize(i + 1);  
                    }  
                      
                    String content = parse(colnames,colTypes,colSizes);  
                      
                    try {  
                        File directory = new File("");  
                        String outputPath = directory.getAbsolutePath()+ "/src/"+this.packageOutPath.replace(".", "/")+"/"+initcap(tablename) + ".java";  
                        String testFile = outputPath.substring(0, outputPath.lastIndexOf("/")+1);
                        File dir = new File(testFile);
                        if(!dir.exists()) {
                        	 dir.mkdirs();
                        }
                        FileWriter fw = new FileWriter(outputPath);  
                        PrintWriter pw = new PrintWriter(fw);  
                        pw.println(content);  
                        pw.flush();  
                        pw.close();  
                    } catch (IOException e) {  
                        e.printStackTrace();  
                    }  
                      
                } catch (SQLException e) {  
                    e.printStackTrace();  
                } finally{  
                    try {  
                        con.close();  
                    } catch (SQLException e) {  
                        e.printStackTrace();  
                    }  
                }  
            }  
            System.out.println("读写完毕！");  
        }  
         /** 
          * Java方法 得到当前数据库下所有的表名  
          * @param con 
          */  
        private List<String> getTableName() {
        	List<String> list=new ArrayList<String>();  
        	if(allTalbe) {
              try {    
                  DatabaseMetaData meta = DriverManager.getConnection(URL,NAME,PASS).getMetaData();    
                  ResultSet rs = meta.getTables(null, null, null,new String[]{"TABLE"});  
                  while (rs.next()) {  
                      //获取当前管理员的表的名称  
                      if(rs.getString(2).equals(NAME.toUpperCase())){  
                          list.add(rs.getString(3));    
                      }  
                  }    
                }catch(Exception e){    
                    e.printStackTrace();    
                }  
        	}else {
        		list = LIST;
        	}
            return list;  
         }  
        /** 
         * 功能：生成实体类主体代码 
         * @param colnames 
         * @param colTypes 
         * @param colSizes 
         * @return 
         */  
        private String parse(String[] colnames, String[] colTypes, int[] colSizes) {  
            StringBuffer sb = new StringBuffer();  
              
            sb.append("package " + this.packageOutPath + ";\r\n");  
            sb.append("\r\n");  
              
            //判断是否导入工具包  
            if(f_util){  
                sb.append("import java.util.Date;\r\n");  
            }  
            if(f_sql){  
                sb.append("import java.sql.*;\r\n");  
            }  
            if(f_jpa){  
                sb.append("import javax.persistence.Entity;\r\n");  
                sb.append("import javax.persistence.GeneratedValue;\r\n");  
                sb.append("import javax.persistence.GenerationType;\r\n");  
                sb.append("import javax.persistence.Id;\r\n");  
            }  
              
            //注释部分  
            sb.append("/**\r\n");  
            sb.append("  * "+tablename+" 实体类\r\n");  
            sb.append("  * "+new Date()+"\r\n");  
            sb.append("  * @"+this.authorName+"\r\n");  
            sb.append("  */\r\n");  
              
            if(f_jpa){  
                sb.append("@Entity\r\n");  
            }  
            //实体部分  
            sb.append("public class " + initcap(tablename) + "{\r\n");  
            processAllAttrs(sb);//属性  
            processAllMethod(sb);//get set方法  
            sb.append("}\r\n");  
              
            return sb.toString();  
        }  
          
        /** 
         * 功能：生成所有属性 
         * @param sb 
         */  
        private void processAllAttrs(StringBuffer sb) {  
              
            for (int i = 0; i < colnames.length; i++) {  
            	sb.append("\t/**\r\n");
            	sb.append("\t*\r\n");
            	sb.append("\t*/\r\n");
            	sb.append("\t@Column(name = \""+colnames[i]+"\")\r\n");
                sb.append("\tprivate " + sqlType2JavaType(colTypes[i]) + " " + lineToHump(colnames[i]) + ";\r\n");  
            }  
              
        }  
      
        /** 
         * 功能：生成所有方法 
         * @param sb 
         */  
        private void processAllMethod(StringBuffer sb) {  
              
        	if(f_setGet) {
        		for (int i = 0; i < colnames.length; i++) {  
        			sb.append("\tpublic void set" + initcap(colnames[i]) + "(" + sqlType2JavaType(colTypes[i]) + " " + colnames[i] + "){\r\n");  
        			sb.append("\t\tthis." + colnames[i] + "=" + colnames[i] + ";\r\n");  
        			sb.append("\t}\r\n");  
        			if(f_jpa){  
        				if(i==0){  
        					sb.append("\t@Id\r\n");  
        					sb.append("\t@GeneratedValue(strategy = GenerationType.AUTO)\r\n");  
        					sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");  
        				}else{  
        					sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");  
        				}  
        			}else{  
        				sb.append("\tpublic " + sqlType2JavaType(colTypes[i]) + " get" + initcap(colnames[i]) + "(){\r\n");  
        			}  
        			sb.append("\t\treturn " + colnames[i] + ";\r\n");  
        			sb.append("\t}\r\n");  
        		}  
        	}
              
        }  
          
        /** 
         * 功能：将输入字符串的首字母改成大写 
         * @param str 
         * @return 
         */  
        private String initcap(String str) {  
              
            char[] ch = str.toCharArray();  
            if(ch[0] >= 'a' && ch[0] <= 'z'){  
                ch[0] = (char)(ch[0] - 32);  
            }  
              
            return new String(ch);  
        }  
      
        /** 
         * 功能：获得列的数据类型 
         * @param sqlType 
         * @return 
         */  
        private String sqlType2JavaType(String sqlType) {  
              
            if(sqlType.equalsIgnoreCase("binary_double")){  
                return "double";  
            }else if(sqlType.equalsIgnoreCase("binary_float")){  
                return "float";  
            }else if(sqlType.equalsIgnoreCase("blob")){  
                return "byte[]";  
            }else if(sqlType.equalsIgnoreCase("blob")){  
                return "byte[]";  
            }else if(sqlType.equalsIgnoreCase("char") || sqlType.equalsIgnoreCase("nvarchar2")   
                    || sqlType.equalsIgnoreCase("varchar2")){  
                return "String";  
            }else if(sqlType.equalsIgnoreCase("date") || sqlType.equalsIgnoreCase("timestamp")  
                     || sqlType.equalsIgnoreCase("timestamp with local time zone")   
                     || sqlType.equalsIgnoreCase("timestamp with time zone")){  
                return "Date";  
            }else if(sqlType.equalsIgnoreCase("number")){  
                return "Long";  
            }  
              
            return "String";  
        }  
          
        /** 下划线转驼峰 */
        public static String lineToHump(String str) {
              str = str.toLowerCase();
           Matcher matcher = linePattern.matcher(str);
            StringBuffer sb = new StringBuffer();
            while (matcher.find()) {
                matcher.appendReplacement(sb, matcher.group(1).toUpperCase());
           }
             matcher.appendTail(sb);
           return sb.toString();
       }
        
        /** 驼峰转下划线(简单写法，效率低于{@link #humpToLine2(String)}) */
        public static String humpToLine(String str) {
              return str.replaceAll("[A-Z]", "_$0").toLowerCase();
           }
        
         private static Pattern humpPattern = Pattern.compile("[A-Z]");
        
           /** 驼峰转下划线,效率比上面高 */
         public static String humpToLine2(String str) {
             Matcher matcher = humpPattern.matcher(str);
            StringBuffer sb = new StringBuffer();
            while (matcher.find()) {
                 matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
             }
              matcher.appendTail(sb);
            return sb.toString();
        }
        /** 
         * 出口 
         * TODO 
         * @param args 
         */  
        public static void main(String[] args) {  
            new GenEntityOracle();  
        }  
      
    }