http断点续传简单实现（java)

/* l/LRr.x  
**SiteFileFetch.java &[I#5bGk  
*/ Xa<siA{  
package NetFox; FlVGi3  
import java.io.*; I=
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import java.net.*; g_>
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public class SiteFileFetch extends Thread { $q.8ve0&^  
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SiteInfoBean siteInfoBean = null; //文件信息Bean :Iwe>;}  
long[] nStartPos; //开始位置 aU4'_%Y@  
long[] nEndPos; //结束位置 ICq;jfML  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 PKdM-R'Z  
long nFileLength; //文件长度 bvEk.~tC'  
boolean bFirst = true; //是否第一次取文件 *KxV;H8/  
boolean bStop = false; //停止标志 }E8 Y,;fTD  
File tmpFile; //文件下载的临时信息 Jd1eOeS  
DataOutputStream output; //输出到文件的输出流 D6bCC; h=  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） k>VP<Zm13  
public SiteFileFetch(SiteInfoBean bean) throws IOException ),bdj+wr78  
{ ^fnRzX  
siteInfoBean = bean; uHz D  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); X/5tZ@  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); U <4<8'  
if(tmpFile.exists ()) M/d!&Bk  
{ 9]NsWd^^  
bFirst = false; .j7|;Ag  
read_nPos(); *PL+)2ob  
} DKIDLf  
else 3p!R4f)GN  
{ _3A$zA  
nStartPos = new long[bean.getNSplitter()]; J[LGa:``  
nEndPos = new long[bean.getNSplitter()]; axU!o /m>  
} aeSy,:  
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} W'gCFX  
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public void run() ODv)-J  
{ n6Q 3X  
//获得文件长度 cY\-e?`=4  
//分割文件 s)/i_Oe$\  
//实例FileSplitterFetch .vpQ3m>  
//启动FileSplitterFetch线程 Qg9{<0{u  
//等待子线程返回 ~Gwn||g78  
try{  Kn\Oj=4  
if(bFirst) 8l!S<RA  
{ L>@0Nne7  
nFileLength = getFileSize(); 4Iy\   
if(nFileLength == -1)  J|6aa  
{ 6_zL#7E'  
System.err.println("File Length is not known!"); Mv4JF(,S  
} Qt>yRt  
else if(nFileLength == -2) f_raICO{R  
{ dqF--)Nb  
System.err.println("File is not access!"); "]MF =-v  
} ;=h^"et  
else HLk}E*.mC  
{ NTAPx=!1*  
for(int i=0;i<nStartPos.length;i++) _Seiwk&  
{ ) 3YE$,  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); P.;B V",  
} [&FMVM`  
for(int i=0;i<nEndPos.length-1;i++) !7%L%~z^  
{ k(VA5upCs  
nEndPos = nStartPos[i+1]; C?hw$^w7T  
} Q~-gtEv+&  
nEndPos[nEndPos.length-1] = nFileLength; 7;|6g8=  
} ;PS[VdV  
} dC,F?^  
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PFEi=}Y@((  
//启动子线程 lX5(KUN
 
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; bGwLfU  
for(int i=0;i<nStartPos.length;i++) /tt  
{ aK1|b=gVj  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), P\N`E?lJL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), g-*@I`k[  
nStartPos,nEndPos,i); h+Dg"j<[  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); II~D66 bF  
fileSplitterFetch.start(); sF|<m)Kt{W  
} ^=R>rUCmv  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ]4z?sk@  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); b;x^>(It  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", O^:Rm=,$  
nEndPos = " + nFileLength); d(To)ly.  
// fileSplitterFetch[nPos.length-1].start(); u1]5qtg"  
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[HNGTde&  
//等待子线程结束 |L`w4;  
//int count = 0; BT#'<!7!  
//是否结束while循环 xTAC&OCk^[  
boolean breakWhile = false; y'4=  
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while(!bStop) |
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{ vaK$j!%FE  
write_nPos(); \f{C2d/6j  
Utility.sleep(500); W*U\79H  
breakWhile = true; AeUwih. 4  
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for(int i=0;i<nStartPos.length;i++) &+*jTE  
{ '>`bp25>  
if(!fileSplitterFetch.bDownOver) pazFVzT  
{ y!aq}YS  
breakWhile = false; Ah)7A|0rT  
break; WfO6Fvx%  
} t~@TUTbx  
} ;TaT=
%  
if(breakWhile) 0Y!Bb2m  
break; O'idS`  
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% ;6e@U}  
//count++; urog.Q  
//if(count>4) }"xC1<]  
// siteStop(); !T @|9PCp  
} :5CwRg  
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System.err.println("文件下载结束！"); %W`pTvF  
} x%x[5.CT  
catch(Exception e){e.printStackTrace ();} ,"}'NH@  
} `^w5/v#  
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//获得文件长度 ADHe![6q  
public long getFileSize() {}lw%d?A  
{ BHFWig*{  
int nFileLength = -1; '-ACNgNn  
try{ (mza&WF7  
URL url = new URL(siteInfoBean.getSSiteURL()); J-I7K!B  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); L'['7  
httpConnection.setRequestProperty("User-Agent","NetFox"); r}vI#;&  
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int responseCode=httpConnection.getResponseCode(); K<|eZhp~  
if(responseCode>=400) n|^-qy'w  
{ A?6b)B/e?  
processErrorCode(responseCode); eUBk^C]\  
return -2; //-2 represent access is error 6= 9  
} *(r85lEou)  
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String sHeader; T]E$H, p  
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for(int i=1;;i++) v3@)q0@  
{ 1 k H  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); wmT3 >  
//Utility.log(in.readLine()); BJlF@F#  
sHeader=httpConnection.getHeaderFieldKey(i); 9 -TFyZYU  
if(sHeader!=null) J.O;c5wL  
{ fh,Y#.V`  
if(sHeader.equals("Content-Length")) 5Z;Py"%  
{ ];Z_S`JR  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); y
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break; /nC"'d(#  
} I98wMV8  
} S liF$}J  
else zHx?-Q&3  
break; v_G4:tY  
} hr)TC-  
} !TG"A
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catch(IOException e){e.printStackTrace ();} r{Fu|aoa;5  
catch(Exception e){e.printStackTrace ();} 6|9];)  
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Utility.log(nFileLength); Kk??}  
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return nFileLength; [i&tE.7  
} lUWjm
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//保存下载信息（文件指针位置） SZyPl9.b  
private void write_nPos()  a_Xh(d$  
{ d5u,x.R  
try{ 12k)Ek9  
output = new DataOutputStream(new FileOutputStream(tmpFile)); -pLb%f0?  
output.writeInt(nStartPos.length); 9K%E+_7b  
for(int i=0;i<nStartPos.length;i++) 4V[+
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{ sb8SG_c.  
// output.writeLong(nPos); Zi|'lHr  
output.writeLong(fileSplitterFetch.nStartPos); H)(Jjk
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output.writeLong(fileSplitterFetch.nEndPos); %Cm4a49FNi  
} L-=^GNh  
output.close(); LTJ|EXYA  
} l?#([(WM  
catch(IOException e){e.printStackTrace ();} _s=[z$EN&  
catch(Exception e){e.printStackTrace ();} iF`E>
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} 'RG`DzuF  

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//读取保存的下载信息（文件指针位置） JbG+ysn  
private void read_nPos() [%bshaY:  
{ gE8>5_R|  
try{ u/hD9g~H7K  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); AoTL)',  
int nCount = input.readInt(); O-:~6A  
nStartPos = new long[nCount]; /S|Pq!4<  
nEndPos = new long[nCount]; W]reQ&<Z  
for(int i=0;i<nStartPos.length;i++) eBBh/=Zc  
{ lYq R6^  
nStartPos = input.readLong(); "_5av!;A g  
nEndPos = input.readLong(); R':a,6O  
} )~!Gs/w6  
input.close(); <hS >L1ZSr  
} 9BHl2<&V  
catch(IOException e){e.printStackTrace ();} @3b0hi4  
catch(Exception e){e.printStackTrace ();} uT;9xV%ch  
} \N;s@j W  
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private void processErrorCode(int nErrorCode) b%pLjvU  
{ EP{y?+E2  
System.err.println("Error Code : " + nErrorCode); 0R*!o\y  
} 1k "*@Z<  
ukhI'alS,  
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//停止文件下载 rsiG]o=8  
public void siteStop() V_Y SYG9f  
{ !QC->  
bStop = true; N!H
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for(int i=0;i<nStartPos.length;i++) 'm-s8]-W  
fileSplitterFetch.splitterStop(); /A{znE  
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} 4UG7{[!+  
} o3%+FWrVTS  
//负责部分文件的抓取 Fet>KacTht  
**FileSplitterFetch.java o2Z# 5-  
*/ H?O*  
package NetFox; X;zy1ZH  
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import java.io.*; M|76,2u   
import java.net.*; =X>?Y,  
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public class FileSplitterFetch extends Thread { c 8E&  
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String sURL; //File URL -_A0<A.  
long nStartPos; //File Snippet Start Position LD#]"k  
long nEndPos; //File Snippet End Position {fk'g(E8([  
int nThreadID; //Thread's ID p?5`+Z  
boolean bDownOver = false; //Downing is over E+[K?W5  
boolean bStop = false; //Stop identical L# (o(4g2  
FileAccessI fileAccessI = null; //File Access interface G9^!= v@  
X@jml$;$  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException u'P@3'P  
{ +FyG{1?<  
this.sURL = sURL; .pG_j]  
this.nStartPos = nStart; 2sWM(SN  
this.nEndPos = nEnd; 7pr@aA"vgj  
nThreadID = id; +dIg&}Tr  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 lts{<AU~  
} J Wof<D,  
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public void run() |<9R%  
{ F8/4PB8-  
while(nStartPos < nEndPos && !bStop) 42X[Huy]  
{ 2z&HT SI  
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try{ /R@eOl}D  
URL url = new URL(sURL); &o:wSe  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); sIg{a(1/  
httpConnection.setRequestProperty("User-Agent","NetFox"); bi[vs|  
String sProperty = "bytes="+nStartPos+"-"; JZ80|-c  
httpConnection.setRequestProperty("RANGE",sProperty); ?v `0KF  
Utility.log(sProperty); [ 98)
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InputStream input = httpConnection.getInputStream(); e3\*Np!rTQ  
//logResponseHead(httpConnection); BTGPP@p4  
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byte[] b = new byte[1024]; YDdmT7Ow  
int nRead; m[(2  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) VbJGyjx  
{ s$|GVv1B  
nStartPos += fileAccessI.write(b,0,nRead); n$B=Vt,  
//if(nThreadID == 1) c?j/H$  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ~B1)!5Z  
} #.#T+B+9  
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Utility.log("Thread " + nThreadID + " is over!"); {N/(lB8  
bDownOver = true; O~l WFaW  
//nPos = fileAccessI.write (b,0,nRead); #tGW|F  
} qeHb0G  
catch(Exception e){e.printStackTrace ();}
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} Kcl>uAgU  
} l]^uVOX  
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//打印回应的头信息 T"XZ[q  
public void logResponseHead(HttpURLConnection con) -7$7TD`'7  
{ DMsxHAE1  
for(int i=1;;i++) QUwSnotgU  
{ ixp(^>ZN  
String header=con.getHeaderFieldKey(i); YN.rj-;^+  
if(header!=null) L
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//responseHeaders.put(header,httpConnection.getHeaderField(header)); .Hc]?R]  
Utility.log(header+" : "+con.getHeaderField(header)); +Ae4LeVzc  
else N'=8Dj  
break; k7'B5zVd  
} ;| )&aTdH  
} [N'YFb3"O  
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public void splitterStop() Y Dq5%N`  
{ I?EtU/AD  
bStop = true; Pur~Rz\\  
} OZB(4{vnyC  
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} pa`"f&JO  
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/* :Bz*vH  
**FileAccess.java ~K&ko8  
*//文件访问(定位，写) iYEhrb
 
package NetFox; -}AAA*P  
import java.io.*; U4w^eWzP
 
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public class FileAccessI implements Serializable{ ncuqo'r  
Q~MV0<{  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 x4r\cL1!  
RandomAccessFile oSavedFile; d *!)wt  
long nPos; j;WZ[g#t  
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public FileAccessI() throws IOException G\@uj>Z  
{  <]2X~+v  
this("",0); 96fbMP+7R  
} lc?9B  
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public FileAccessI(String sName,long nPos) throws IOException 5 <X.1T1  
{ k2(B{x}L  
oSavedFile = new RandomAccessFile(sName,"rw"); p~J|l$%0rQ  
this.nPos = nPos; Po~{Mpe  
oSavedFile.seek(nPos); ,9SBGxK5`  
} w@ALl#z;}  
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public synchronized int write(byte[] b,int nStart,int nLen) (&H-v'a}3  
{ H$bu*o-Z  
int n = -1; 0hVw=KDO9:  
try{ outAZy=R;  
oSavedFile.write(b,nStart,nLen); Q`j!$r  
n = nLen; 0<d9al|J  
} e%Rg,dX  
catch(IOException e) yU<T_&
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{ __dSEOGoe  
e.printStackTrace (); ?Imq4I~)  
} !VBl/ aU@  
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return n; f*)8bZDD  
} >rJ9^rS  
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} Gi]R8?M  
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/* E}LYO:  
**SiteInfoBean.java 4HG;v|Cp  
*/ XRARgWj  
package NetFox; #X1iig+  
9f1,E98w_  
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public class SiteInfoBean { Wwo'pke  
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private String sSiteURL; //Site's URL j]Y`L?!Q  
private String sFilePath; //Saved File's Path 82d~>i%T  
private String sFileName; //Saved File's Name WD.td  
private int nSplitter; //Count of Splited Downloading File hilgl<
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public SiteInfoBean() moz*=a  
{//nSplitter的缺省值为5 `#J0@ -  
//default value of nSplitter is 5 sa6/$  
this("","","",5); 4
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} %+gK5aVab  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter)
nD#QC=}  
{ QAN :  
sSiteURL= sURL; V&e9?5@  
sFilePath = sPath; &}}UdJ`  
sFileName = sName; fib#)KE  
this.nSplitter = nSpiltter; d!>.$|b  
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} 'Z;8-1M?O  
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public String getSSiteURL() 5 1&||.  
{ 1V/?p<A  
return sSiteURL; Z@sDxYt9  
} X"hdCY%  
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' 5tk0A  
public void setSSiteURL(String value) q)N]*~  
{ ^UJB%l  
sSiteURL = value; KAkD" (!  
} =Pj+^+UM  
$F&m('aB8  

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public String getSFilePath() J]mG!#9  
{ #M/^n0E  
return sFilePath; bn*SLWWQ.3  
} *.F^`]yz  
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public void setSFilePath(String value) v^A4%e<8^r  
{ OS- Xh-:z  
sFilePath = value; zv.R~lMtY  
} $tm%=g^  
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public String getSFileName() ^mp#7OL  
{ 9I1D'7wI^^  
return sFileName; Q{K'#  
} O%m\ Q1  
"39\@Ow  
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public void setSFileName(String value) >v?&&FhHK<  
{ nXRT%[o&  
sFileName = value; \5 S^~(iL  
} ),!1B%  
H\vd0DD;  
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public int getNSplitter() m.6O%jD  
{ UgD|tuz]  
return nSplitter; 1U?,}w  
} `xXpP"*o}  
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Ez)hArxns  
public void setNSplitter(int nCount) w ag^Sk  
{ MJ?fMR@  
nSplitter = nCount; %$Smei
 
} 5|<jPc  
} ](@HPAG]  
7$zeRYD+  
#Ch*a.tI@  
/* ~vPR9\e  
**Utility.java .D8|_B  
*/ [C-4*qOaa2  
package NetFox; .91@T.  
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public class Utility { N e<D'-  

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chC= $(5t  
public Utility() _uf,7R-  
{ DWwPid} "  
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F$6JzF$|F  
} Mil+> X0  
~[@gu,Wb  
//线程睡眠 w\}@+w3b~  
public static void sleep(int nSecond) GZt L-  
{ %iq8
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try{ \#(tI3  
Thread.sleep(nSecond); &02I-lD4+  
} G^%FP!'D?  
catch(Exception e) 0d|DIT#>?  
{
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e.printStackTrace (); 7TU(~]Z  
} S*3*Q l*  
} YQ-!>3/)-  
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//日志 [:BD9V  
public static void log(String sMsg) cF V[k'F  
{ Cm"7f!(#  
System.err.println(sMsg); oniVC',  
} Jk=_8Xvr`  
q).["fSV  
FGey%:p9$  
public static void log(int sMsg) <y2HzBC  
{ +5i~}Q!  
System.err.println(sMsg); q@=3`yQ  
} 7.y35y  
} mDdL7I  
LX8A@Yct  
 DJJd_  
/* UbDpSfub  
**TestMethod.java  -]. a0  
*/ MHqk-4Mz  
package NetFox; g-LMct8$  
KD* xFap  
|>zYUT[V  
public class TestMethod { 80GBkFjV  
dRL*TT0NW  
k-!Jww  
public TestMethod() zI.%b7wq  
{ ///xx/weblogic60b2_win.exe e.VQ!)>  
try{ B{tROuN<  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); f`K[oCfu  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 5HC5   
SiteFileFetch fileFetch = new SiteFileFetch(bean); Ly P Cc|  
fileFetch.start(); $)#?4v<  
} /e;E+   
catch(Exception e){e.printStackTrace ();} wTe 9OFv  
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} oJ.5! Kg  
#ZyY(S1.  
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public static void main(String[] args) j"r7M|Z+V  
{ (.pi,+Ws  
new TestMethod(); !O 0{ .k  
} ],-(YPiAD  
} `lcQ Yd<,4  
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