java如何实现自动生成数据库设计文档

实现Java自动生成数据库设计文档的过程可以分为以下几个步骤：

1. 获取数据库的基本信息

首先需要连接到数据库，获取其中的基本信息，例如数据库的名称、版本号等。在Java中可以使用JDBC连接数据库，通过执行SQL语句获取这些信息。

1. 获取数据库中的表信息

获取数据库中的表信息，包括表名、表的列信息等。可以通过执行SQL语句查询system表或metadata元数据信息来获取。

1. 生成数据库文档

根据获取到的数据库基本信息和表信息，生成数据库设计文档。可以使用自定义的模板引擎，将获取到的信息填充到指定的模板中，生成最终的文档。

以下是两条示例：

示例一

获取数据库基本信息

String url = "jdbc:mysql://localhost:3306/test";
String username = "root";
String password = "123456";

Connection conn = DriverManager.getConnection(url, username, password);
DatabaseMetaData metaData = conn.getMetaData();

System.out.println("数据库名称：" + metaData.getDatabaseProductName());
System.out.println("数据库版本号：" + metaData.getDatabaseProductVersion());

获取表信息

ResultSet rs = metaData.getTables(null, null, null, new String[] {"TABLE"});
while (rs.next()) {
    String tableName = rs.getString("TABLE_NAME");
    String remarks = rs.getString("REMARKS");
    System.out.println("表名：" + tableName + "，注释：" + remarks);
}

生成文档

使用FreeMarker模板引擎生成文档：

Template template = configuration.getTemplate("doc.ftl");
Map<String, Object> root = new HashMap<>();
root.put("databaseName", metaData.getDatabaseProductName());
root.put("databaseVersion", metaData.getDatabaseProductVersion());
root.put("tables", tables);
Writer out = new FileWriter(new File("database.doc"));
template.process(root, out);
out.close();

完整代码

String url = "jdbc:mysql://localhost:3306/test";
String username = "root";
String password = "123456";

Configuration configuration = new Configuration(Configuration.getVersion());
configuration.setClassForTemplateLoading(Main.class, "/templates");
Template template = configuration.getTemplate("doc.ftl");

Connection conn = DriverManager.getConnection(url, username, password);
DatabaseMetaData metaData = conn.getMetaData();

List<Table> tables = new ArrayList<>();
ResultSet rs = metaData.getTables(null, null, null, new String[]{"TABLE"});
while (rs.next()) {
    String tableName = rs.getString("TABLE_NAME");
    String remarks = rs.getString("REMARKS");
    Table table = new Table(tableName, remarks, new ArrayList<>());
    ResultSet rs2 = metaData.getColumns(null, null, tableName, null);
    while (rs2.next()) {
        String columnName = rs2.getString("COLUMN_NAME");
        String columnType = rs2.getString("TYPE_NAME");
        String columnRemark = rs2.getString("REMARKS");
        table.getColumns().add(new Column(columnName, columnType, columnRemark));
    }
    tables.add(table);
}
Map<String, Object> root = new HashMap<>();
root.put("databaseName", metaData.getDatabaseProductName());
root.put("databaseVersion", metaData.getDatabaseProductVersion());
root.put("tables", tables);

Writer out = new FileWriter(new File("database.doc"));
template.process(root, out);
out.close();

示例二

获取数据库基本信息

使用连接池方式获取数据库连接，从连接中获取元数据信息：

MysqlDataSource dataSource = new MysqlDataSource();
dataSource.setUser("root");
dataSource.setPassword("password");
dataSource.setURL("jdbc:mysql://localhost:3306/test");
Connection connection = dataSource.getConnection();
DatabaseMetaData metaData = connection.getMetaData();
System.out.println("数据库名称：" + metaData.getDatabaseProductName());
System.out.println("数据库版本号：" + metaData.getDatabaseProductVersion());

获取表信息

使用JdbcTemplate执行SQL获取表信息：

List<Table> tables = new ArrayList<>();
jdbcTemplate.query("SELECT TABLE_NAME,TABLE_COMMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ?", new Object[] {dataSource.getDatabaseName()}, rs -> {
    String tableName = rs.getString("TABLE_NAME");
    String comments = rs.getString("TABLE_COMMENT");
    Table table = new Table();
    table.setName(tableName);
    table.setComment(comments);
    List<Column> columns = new ArrayList<>();
    jdbcTemplate.query("SELECT COLUMN_NAME,COLUMN_TYPE,COLUMN_COMMENT FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ?", new Object[] {dataSource.getDatabaseName(), tableName}, rs2 -> {
        String columnName = rs2.getString("COLUMN_NAME");
        String columnType = rs2.getString("COLUMN_TYPE");
        String columnComment = rs2.getString("COLUMN_COMMENT");
        columns.add(new Column(columnName, columnType, columnComment));
    });
    table.setColumns(columns);
    tables.add(table);
});

生成文档

使用Freemarker模板引擎生成文档：

Template template = configuration.getTemplate("doc.ftl");

Map<String, Object> root = new HashMap<>();
root.put("databaseName", databaseName);
root.put("databaseVersion", metaData.getDatabaseProductVersion());
root.put("tables", tables);

Writer out = new FileWriter(new File(outputFile));
template.process(root, out);
out.close();

完整代码

MysqlDataSource dataSource = new MysqlDataSource();
dataSource.setUser("root");
dataSource.setPassword("password");
dataSource.setURL("jdbc:mysql://localhost:3306/test");

JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);

DatabaseMetaData metaData = dataSource.getConnection().getMetaData();

List<Table> tables = new ArrayList<>();
jdbcTemplate.query("SELECT TABLE_NAME,TABLE_COMMENT FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = ?", new Object[] { dataSource.getDatabaseName()}, rs -> {
    String tableName = rs.getString("TABLE_NAME");
    String comments = rs.getString("TABLE_COMMENT");
    Table table = new Table();
    table.setName(tableName);
    table.setComment(comments);
    List<Column> columns = new ArrayList<>();
    jdbcTemplate.query("SELECT COLUMN_NAME,COLUMN_TYPE,COLUMN_COMMENT FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = ? AND TABLE_NAME = ?", new Object[] { dataSource.getDatabaseName(), tableName}, rs2 -> {
        String columnName = rs2.getString("COLUMN_NAME");
        String columnType = rs2.getString("COLUMN_TYPE");
        String columnComment = rs2.getString("COLUMN_COMMENT");
        columns.add(new Column(columnName, columnType, columnComment));
    });
    table.setColumns(columns);
    tables.add(table);
});

Configuration configuration = new Configuration(Configuration.getVersion());
configuration.setClassForTemplateLoading(this.getClass(), "/templates");
Template template = configuration.getTemplate("doc.ftl");

Map<String, Object> root = new HashMap<>();
root.put("databaseName", dataSource.getDatabaseName());
root.put("databaseVersion", metaData.getDatabaseProductVersion());
root.put("tables", tables);

Writer out = new FileWriter(new File(outputFile));
template.process(root, out);
out.close();