java - 如何使用 BeanUtils 转换器来列表？

Question

这里，请求参数字符串是:

firstName=jack&lastName=lily&gender=1&foods=Steak&foods=Pizza&quote=Enter+your+favorite+quote!&education=Jr.High&tOfD=Day

映射类是:

public class Student {
    private String firstName;
    private String lastName;
    private Integer gender;
    private List<String> foods;
    private String quote;
    private String education;
    private String tOfD;

    getXxx()....;
    setXxx()....;
}

现在，我想编写一个通用的 util 类来将字符串转换为 bean。

public final class InjectUtil<T> {
private static final Logger LOGGER = LoggerFactory.getLogger(InjectUtil.class);

public static <T> T converter2Obj(String source, Class<T> tClass) {
    T t = null;
    try {
        t = tClass.newInstance();

        if(source != null && source.length() > 0) {
            String[] fields = source.split("&");
            for(String field : fields) {
                String[] fieldKeyValue = field.split("\\=");
                String fieldKey = fieldKeyValue[0];
                String fieldValue = fieldKeyValue[1];
                // help
            }
        }
    } catch(InstantiationException | IllegalAccessException | InvocationTargetException e) {
        e.printStackTrace();
    }
    return t;
}

}

请照顾帮助，我如何使用 BeanUtils 转换器将“foods=Steak&foods=Pizza”转换为 List 属性。

Answer 1

这是一种实现方法:

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.beanutils.BeanUtils;

public final class InjectUtil<T> {
    // private static final Logger LOGGER =
    // LoggerFactory.getLogger(InjectUtil.class);

    public static <T> T converter2Obj(String source, Class<T> tClass) {
        T t = null;

        try {
            t = tClass.newInstance();
            Map<String, Object> params = new HashMap<String, Object>();
            if (source != null && source.length() > 0) {
                String[] fields = source.split("&");
                for (String field : fields) {
                    String[] fieldKeyValue = field.split("\\=");
                    String fieldKey = fieldKeyValue[0];
                    String fieldValue = fieldKeyValue[1];

                    if (params.containsKey(fieldKey)) {

                        //the key does not exist as yet
                        Object keyValueRetrieved = params.get(fieldKey);
                        if (keyValueRetrieved instanceof String) {
                            //key exists , it is single value that has been added now.
                            //change that now to a list to add more values
                            ArrayList<String> values = new ArrayList<String>();
                            values.add(keyValueRetrieved.toString());
                            values.add(fieldValue);
                            params.put(fieldKey, values);
                        } else {
                            //key exists , it is a list already. Add more values
                            ((ArrayList<String>) keyValueRetrieved).add(fieldValue);
                        }
                    } else {
                        params.put(fieldKey, fieldValue);
                    }

                }
            }
            BeanUtils.populate(t, params);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("--------------------------------------------");
        System.out.println(t.toString());
        System.out.println("--------------------------------------------");
        return t;
    }
}

您可以进行一些优化，希望这能给您一个想法