Question

我正在研究android，而不是Manjo这个主题从现在开始，我想创建一个简单的MVC CRUD，其中model.save想要绘制（）;

我试图检索我在MainActivity中配置的值

所以我创建了以下结构：

MainActivity.java

Produto produto1 = new Produto(this);
produto1.setId(1);
produto1.setNome("CELULAR");
produto1.setPreco(5.5);
produto1.Save();

Produto.java

@DatabaseTable (tableName = "produtos") 
public class Produto extends BaseModel{

     @DatabaseField(columnName="id",    columnType="INTEGER", primaryKey=true)
     private int id;

     @DatabaseField(columnName="nome", columnType="VARCHAR")
     private String nome;

     @DatabaseField(columnName="preco", columnType="DOUBLE", columnSize="10,9")
     private Double preco;

     @DatabaseField(columnName="endereco", columnType="TEXT", columnSize="50", canBeNull=true, defaultValue="NULL", unique=true)
     private Double endereco;

     public int getId() {return id;}
     public void setId(int id) {this.id = id;}
     public String getNome() {return nome;}
     public void setNome(String nome) {this.nome = nome;}
     public Double getPreco() {return preco;}
     public void setPreco(Double preco) {this.preco = preco;}

     public Produto(Context context) {
         super(context);
     }  
}

DatabaseTable.java

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE) //can use in method only.
public @interface DatabaseTable {
    String tableName();  
}

DatabaseField.java

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD) //can use in method only.
public @interface DatabaseField {
     String columnName() default "";  
     String columnType(); 
     String defaultValue() default "";
     String columnSize() default "";
     boolean canBeNull() default true; 
     boolean unique() default false; 
     boolean primaryKey() default false; 
     boolean autoIncrement() default false; 
}

BaseModel.java

public class BaseModel extends DBFactory<BaseModel> {
 public BaseModel(Context context) {
      super(context);
 }
}

DBFactory.java

public class DBFactory<T> extends SQLiteOpenHelper {
    private static final String DB_NAME = "VendasDB";
    private static final int DATABASE_VERSION  = 1;
    private final Context myContext;
    private static DBFactory mInstance = null;
    private static SQLiteDatabase myWritableDb;

    private Class t;
    public void set(Class t) { this.t = t; }
    public Class get() { return t; }

    public DBFactory(Context pContext){         
        super(pContext, DB_NAME, null, DATABASE_VERSION);
        this.myContext = pContext;
        this.set((Class) this.getClass());    
        Log.v("CreateTableOnModel",CreateTableOnModel());
    }

    public String Save()
    {
        Log.v("DBFactory", "SAVE()");
        Class clazz = get();

        DatabaseTable annot = (DatabaseTable) clazz.getAnnotation(DatabaseTable.class);
        StringBuilder sb = new StringBuilder();

        if(!annot.tableName().equals(""))
        {
            Field[] fields = clazz.getDeclaredFields();
            Field idField = null;

            try {
               idField = clazz.getDeclaredField("id");      
               idField.setAccessible(true);
               Object b = idField.get(get().newInstance());
               Log.v("idField:", b.toString());
            } catch (Exception nsfe) {
               System.out.println(nsfe.toString());
            }


        }
    }
}

03-31 16:26:23.780: I/System.out(32048): java.lang.InstantiationException: can't instantiate class br.com.rlsystem.vendas.model.Produto; no empty constructor

Android getDeclaredFields获得价值

0 个答案: