www.pudn.com > ThinkinginJava4thEdition(SourceCode).zip > TableCreator.java

//: annotations/database/TableCreator.java 
// Reflection-based annotation processor. 
// {Args: annotations.database.Member} 
package annotations.database; 
import java.lang.annotation.*; 
import java.lang.reflect.*; 
import java.util.*; 
 
public class TableCreator { 
  public static void main(String[] args) throws Exception { 
    if(args.length < 1) { 
      System.out.println("arguments: annotated classes"); 
      System.exit(0); 
    } 
    for(String className : args) { 
      Class cl = Class.forName(className); 
      DBTable dbTable = cl.getAnnotation(DBTable.class); 
      if(dbTable == null) { 
        System.out.println( 
          "No DBTable annotations in class " + className); 
        continue; 
      } 
      String tableName = dbTable.name(); 
      // If the name is empty, use the Class name: 
      if(tableName.length() < 1) 
        tableName = cl.getName().toUpperCase(); 
      List columnDefs = new ArrayList(); 
      for(Field field : cl.getDeclaredFields()) { 
        String columnName = null; 
        Annotation[] anns = field.getDeclaredAnnotations(); 
        if(anns.length < 1) 
          continue; // Not a db table column 
        if(anns[0] instanceof SQLInteger) { 
          SQLInteger sInt = (SQLInteger) anns[0]; 
          // Use field name if name not specified 
          if(sInt.name().length() < 1) 
            columnName = field.getName().toUpperCase(); 
          else 
            columnName = sInt.name(); 
          columnDefs.add(columnName + " INT" + 
            getConstraints(sInt.constraints())); 
        } 
        if(anns[0] instanceof SQLString) { 
          SQLString sString = (SQLString) anns[0]; 
          // Use field name if name not specified. 
          if(sString.name().length() < 1) 
            columnName = field.getName().toUpperCase(); 
          else 
            columnName = sString.name(); 
          columnDefs.add(columnName + " VARCHAR(" + 
            sString.value() + ")" + 
            getConstraints(sString.constraints())); 
        } 
        StringBuilder createCommand = new StringBuilder( 
          "CREATE TABLE " + tableName + "("); 
        for(String columnDef : columnDefs) 
          createCommand.append("\n    " + columnDef + ","); 
        // Remove trailing comma 
        String tableCreate = createCommand.substring( 
          0, createCommand.length() - 1) + ");"; 
        System.out.println("Table Creation SQL for " + 
          className + " is :\n" + tableCreate); 
      } 
    } 
  } 
  private static String getConstraints(Constraints con) { 
    String constraints = ""; 
    if(!con.allowNull()) 
      constraints += " NOT NULL"; 
    if(con.primaryKey()) 
      constraints += " PRIMARY KEY"; 
    if(con.unique()) 
      constraints += " UNIQUE"; 
    return constraints; 
  } 
} /* Output: 
Table Creation SQL for annotations.database.Member is : 
CREATE TABLE MEMBER( 
    FIRSTNAME VARCHAR(30)); 
Table Creation SQL for annotations.database.Member is : 
CREATE TABLE MEMBER( 
    FIRSTNAME VARCHAR(30), 
    LASTNAME VARCHAR(50)); 
Table Creation SQL for annotations.database.Member is : 
CREATE TABLE MEMBER( 
    FIRSTNAME VARCHAR(30), 
    LASTNAME VARCHAR(50), 
    AGE INT); 
Table Creation SQL for annotations.database.Member is : 
CREATE TABLE MEMBER( 
    FIRSTNAME VARCHAR(30), 
    LASTNAME VARCHAR(50), 
    AGE INT, 
    HANDLE VARCHAR(30) PRIMARY KEY); 
*///:~